Drinking water regularly doesn't mean you aren't dehydrated though. In fact if you always have a water bottle with you (can't leave home without one), then that is actually a behavior of diabetes insipidus. You can look up diabetes insipidus to see if it sounds like you. This isn't the traditional diabetes you hear on the news. It has absolutely NOTHING to do with blood sugar levels and I suffer from it because of the mercury.

You said that you have hyperactive thyroid. How was this diagnosed? Did they do the appropriate tests other than just checking TSH?

I think a lot more people suffer from pituitary problems than recognized in mainstream medicine. Mercury loves the pituitary, which can affect the thyroid, adrenals and practically every single hormone in the body. The pituitary is what makes TSH (not the thyroid), so you could have an underactive pituitary gland causing secondary hyperthyroidism. You have to just find a doctor that is willing to check the pituitary and knows what they are doing. Most of them don't even consider it unless it isn't working at all or making you gigantic from growth hormone. They fail at diagnosing gray areas.

Another thing to check is your blood pressure. See what it is whenever you feel the heart palpitations. It could be that your blood pressure has fallen so your heart is trying to compensate for it (or you'd faint).

I still think B-12 shots could help you with the numbness. My doctor used both the hydro and methyl form and they both worked to alleviate the numbness.