I feel your pain. I've spent the past 9 months recovering from my thyroid dysfunction. Luckily I haven't had a job so I could spend all my time researching and figuring out how to save myself. Doctors' haven't been much help, other than to let me have blood work done. Fortunately, I had success with my self-experimentation, and I'm basically "cured" and feeling better than I have in 10 years.
I'm guessing you've already read a lot yourself, and tried plenty. So I will try to keep this to the stuff that I figured out and that I haven't heard much talk about:
1) Riboflavin - critical for thyroid function and generally overlooked. Deficiency in riboflavin will cause photophobia, dry eyes. When it gets worse, it leads to a dry throat that leads you to feel like you need to clear your throat all the time. Thyroid dysfunction inhibits riboflavin metabolism. And conversely, riboflavin deficiencies affect the thyroid. It's a vicious cycle with riboflavin.
It tastes minty, and bitter all at the same time. But you will get used to it.
2) Thiamine - another critical b vitamin for thyroid dysfunction. If you occasionally get that racing heart, or pounding feeling, or feel irritable, you are low on thiamine. Studies show this to be very important for hyperthyroidism. You don't need a co-enzyme version - any version will do. But you probably need to take it every few hours. Anytime you take the riboflavin, take 50mg of thiamine. You cannot overdose on riboflavin or thiamine. Magnesium is also needed for thiamine metabolism, but I'm sure you've already been told to take plenty of Magnesium. Magnesium and thiamine work together to protect the heart. I prefer this one:
3) Vitamin A - another vitamin generally not mentioned enough for thyroid dysfunction. I haven't even read of any others using vitamin A for their thyroid issues. Doctors are timid about vitamin A because excess is not easily removed by the body and can cause liver problems. And unlike vitamin D, there is no simple blood test for vitamin A levels. But with your eye symptoms and history, you are no doubt deficient in vitamin A. Especially if you have poor night vision, and if your skin looks yellow when you wear black. Thyroid dysfunction leads to a vitamin A deficiency because you do not convert beta-carotene into retinal esters. You need vitamin A for liver function, and immune function. You might find your allergies improve after a few months of supplementing. Mine have. Best food sources of vitamin A are beef liver, chicken liver and egg yolks. These are not generally popular today. I think many people with a variety of health issues, especially women, are simply deficient in vitamin A. Pregnancy and breastfeeding, and subclinical thyroid problems lead to deficiency without supplementation.
How much to take? A study done on the thyroid had women take 25,000 IU for four months.
It's a good idea to avoid alcohol completely while taking vitamin A. It can be dangerous to take vitamin A and drink alcohol. And anyway, alcohol sucks all the vitamins out of your liver, and that's the last thing you need. I made this mistake - one night of drinking more than my share, and I was set back two months in my recovery. I would avoid all liver detoxes as well. You don't need to cleanse your liver, you need to restock it with nutrients. It's the liver's job to do the cleansing, and the liver needs nutrients to do it's job.
I started taking vitamin A a few months ago. At first, it made me feel so energetic I baked six dozen cookies in a weekend. Prior to that I was mostly a couch potato! I probably should have ramped up slowly, but I took 100,000 IU dose of Vitamin A after researching it, and felt amazing. I also felt a strange burning behind my sternum - which is where the thymus gland is. It lasted for four days. If you feel this, like a very mild but constant ache feeling, it's a good sign. It's not heartburn. It is your thymus gland finally getting nutrients and growing back. The thymus gland is responsible for the differentiation of T cells - your immune cells.
I also experienced a weird eyelash soreness after the vitamin A, and I had some redness in my upper eyelids where the veins are. Since then, my recurring eyelid styes have gone away.
Also, three months later, and for the first time in 15 years, I have been able to stop taking my allergy medication. Prior to now I was on Singular, Zyrtec, Flonase, Pseudoephedrine, and Mucinex. Year round! Plus ten years of allergy shots. I am still kind of in disbelief about this.
Vitamin A is also required for iron metabolism. It helps transport iron to the bone marrow where new red blood cells are made. Vitamin A is not only for vision, but so much more. I could really go on and on about vitamin A. There is still so much we don't know about it's function in the body. Most of the research I found was for third world countries where vitamin A deficiency is epidemic.
4) Now, to address why you went from low thyroid to hyperthyroid. A theory that makes sense is that various nutritional deficiencies resulted in low thyroid function. Then your body adapted, and created a little nodule to make mostly T3. The thyroid normally makes mostly T4 and only a little T3, in a ratio of 11:1. A nodule is often not felt but could be seen with an ultra sound. Doctors will tell you to have it removed. But you can instead take large doses of iodine, like 7,000 mcg or higher, and this will help your thyroid switch back to mostly T4, and a little T3. My mother-in-law had several large nodules that disappeared after taking 12,500 mcg Iodoral tablets daily for three months.
I recommend you start low, with iodine, like 150 mcg, and see how you feel. But you may find small amounts make you feel "hyper". If that happens you should jump up quickly to a large dose. Flooding the thyroid with Iodine will slow it down, which is what you want. You want your thyroid to be like "hey, I don't need to focus on making T3 because now I have all this iodine, so I can make T4, which requires more Iodine to make than T3 does. Don't do the Iodine loading the same week as you do the vitamin A. Start with vitamin A first. Wait few weeks, then try the iodine.
5) Other nutrients to take: B6, B3, methyl versions of B12 and Folate ... okay just a B complex would be best. Again, a co-enzyme sublingual b-complex is your best bet when your thyroid is in dysfunction because it means your ability to absorb and convert these vitamins is compromised. I like this one:
6) More nutrients: you need copper for vitamin A and iron usage. You need zinc and selenium as well. You're probably getting enough of these from food, but might be a good idea to take a trace mineral supplement that has enough copper. A lot of them have too much zinc, not enough copper. For every 15mg of zinc, you need 2 mg of copper.
7) Iron is important for making thyroid hormones. Even a borderline low iron level will interfere with your recovery from thyroid dysfunction. You can get your ferritin checked first, to make sure, but I have found iron to REALLY help me and my ferritin was "normal", right on the low end of the range. I take MegaFood Blood Builder.
8) With all these supplements, it's important to know when and how to take them because there are interactions and certain things will cancel each other out.
In general, the B-vitamins can be taken anytime, and many times a day.
With the exception of folate, which interferes with Zinc in a meal.
Iron should generally be taken alone with only vitamin C, and a lot of it.
Vitamin A and D should be take with food containing fat.
Too much zinc will lead to copper deficiency - don't take more than 30-50mg a day, depending on your weight.