read andrew cutler's book 'amalgam illness'(which is not just about amalgams)... not an easy read, more like a chemistry course, but easily the best hard Science book on the subject of metal poisoning.
do the hair mineral test to check your mineral ratios.
selenium and Iodine are both thyroid nutrients. Iodine will help to feed the thyroid gland and selenium will help to convert thyroxine (sic?) into useable t3 ( liothyronine). some people take much higher doses of Iodine than you are taking, not that i am recommending one way or the other.
see how you do with a high sulfur diet and a low sulfur diet.
you have multiple issues, thyroid, adrenal, nervous system, digestive. occam's razor would indicate a single cause.
try to get your minerals from food in the meantime.
the herb/flower marigold is very gentle and can help settle your nerves and possible digestion a bit.
if you are sufficiently hydrated i would suggest a sauna, but you may be sodium deficient right now and that would make you feel worse until your sodium levels get back up.