Your adrenals and thyroid are stressed and you need to rebuilt them for awhile. I don't want to say your stuck in a trauma loop but you might be. Stress comes in many forms.
A virus or bacteria
Too much exercise
The list goes on and on. Put a few of these together and your body starts to give. First your thyroid is effected causing itchy scalp, dry skin, and hair loss. Then your adrenals start to get stressed causing circles under your eyes, belly fat and muscles loss. Belly fat is a sign of cortisol going up. Insomnia is probably from cortisol as well. When you work out your cortisol goes up effecting your sleep that night. The dizzy feeling is you adrenal straining. You need to take some Sea Salt . Try one Tablespoon a day and see if that helps. You may need a little less or more. Your thyroid can still be running low but not showing up on test. Go to some that test every aspect of they thyroid. Raw Coconut oil and Hemp oil also stimulate the thyroid but it does take awhile to kick in.
I am sorry to tell you this but you need to chill on the workouts. You have to rest for awhile or just do light exercise. You have to let your body rebuilt and repair. You have to calm your mind down too. I did brain retraining because I got really sick and my mind was stuck in a trauma loop. It helped immensely and it was very important to my healing. Also amino acids are super important to you right now. It take about 6 months to a year to rebuild you happy amino acids that your brain needs to calm down. Take minerals and back off on carbs. If you want to see where you are get a 24hr cortisol test and neurotransmitter test. I know it's really not great to have health issues when you felt like you were doing all the right things and it adds to the stress.