This is the first time I've even /heard/ of selenium chloride O_o;
Chloride is the element that is reccommended for use when you need to detox bromide. It's the secret weapon for when using Iodine makes someone as cranky and moodswinging and teary that it looks like mental illness- because with Iodine displacing bromides and other halides from Iodine receptors and into the bloodstream, the brain goes wonk. The documentation on what bromide detox looks like and the list of symptoms is here:
A salt flush uses sodium /chloride/ to shunt out bromides from the bloodstream
The problem definately looks to me like it's a matter of the wrong formulation of selenium. The body loves sulfur-bound selenium best, and once the two are bound together, it's much smoother sailing. Chloride..
In addition to its functions as an electrolyte, chloride combines with hydrogen in the stomach to make hydrochloric acid, a powerful digestive enzyme that is responsible for the break down of proteins, absorption of other metallic minerals, and activation of intrinsic factor, which in turn absorbs vitamin B12.
'' ( http://www.traceminerals.com/research/chloride )
So your thyroid was swelling and you had joint and muscle pain- selenium is used primarily in those areas, but once the selenium molecule was used, you had free chloride in those areas? It's possible there was some extra hydrochloric acid being formed in the anatomy. Selenium has the funtion of reducing hydrochloric acid in the thyroid, (irony of ironies), but I haz the feels...
That more selenium chloride tossed on the fire wooouuldn't put out the blaze.
Now don't get mistaken.. Both chloride and selenium, independantly of eachother, are most excellent things..
But the supplements market is a creepy jungle, and them flavors of selenium come in a wide variety!
If the thyroid and muscle pains continue after a change in selenium supplement (to the bioavailable selenomethionine and selenocysteine forms), then you gotta grab the tri-methyl-glycine (or juice some beetroots. Fun with chemi-in-the-kitchen! 8) ) Beetroot juice is rather one of those.. potent health tonics. It's got Vit C, folate, TMG, everal B's, lotsa bioflavanoids, and no wonder the mideivil folk thought of it as a gooood aphrodesiac! ;) It can indeed make you a bit frisky.