Maybe we could look at the problem of your Thyroid problem from the stand point of like an old Bolt with threads which has been allowed to become Rusty!
Now just how do you suppose , if the threads of the bolt were allowed to become Rusty, just how easy may it be to Thread the Nut onto the Rusty Threads of the bolt!
The same may be for your Thyroid, If it has been allowed to become Rusty in it's duties of operation, then how do you suppose it may be to bring your Thyroid back into proper use?
Do you think that "IF" your Thyroid has become Rusty over the years in not doing it's proper Duties because of a Lack of the proper Electrical Energy, that maybe it may not want to start up without some grinding action?
Or you may look at your Thyroid like a engine which has been allowed to sit and the piston walls have been allowed to rust up, then when you try to crank the engine over, that the pistons may lock up the engine!
So what may be best for you, since it is possible that your thyroid gland is not working properly, may be to start very slowly with the Kelp, as to use only a very small amount , but more often, so as to help your Thyroid Gland to be able to start rebuilding it's self!
For the Thyroid Gland must have Iodine in the organic form , like which is in the Kelp and also may need the other Alkaline Minerals which are in the Kelp also, to help the Thyroid become Healthy again and to function properly!
Now you say that you have Pain when you have taken some Kelp?
Let us consider this idea, also?
Pain may be Greatest when one is too Acidic, this may allow the Pain to be felt much greater!
Now when an area of the body which is in very Acidic condition and you cause too much Alkaline substance to come in contact with this Acidic condition, there may be Heat created when the Acidic condition comes in contact with the Alkaline Minerals in too Great of an amount and you may feel some discomfort as this takes place!
So it may be best, when one is in very bad shape, to take things very slowly, in the process of trying to Heal the body!
Also if you take some extra Calcium each day, this may help buffer your problems which seem to be bothering you!
Smile Tis your choice.