after an "amen" to what ferventer said, this sounds like a basic metabolism crash. its not just the thyroid or the adrenals, its a body thats been made to do things without the materials to do it. after a while the systems shut down and chemical processes that took a few steps now take many.
diet and lifestyle, as they say. what are you deficient in? fresh air? sunshine? clean water? salt? oils? enzymes?
if you do what the tv and doctors say youre screwed.
do the basics of cleansing and flushing and fasting and hydrating. until you do youre just tickling the dragon with that little amount of iodine. if you have mercury in your mouth youre tickling a whole herd of dragons.