the selenium can also stir up mercury, but it sounds like you are well-versed.
all of your symptoms fit into hypothyroid as well which i'm sure you also know.
the startling sounds like adrenal burn-out.
mercury could be the root cause. it is a crap shoot as to what will happen once the fillings come out. some people get worse. i opted to have mine taken out a long time ago, well before andrew cutler wrote his book and i had to feel my way through this morass. the short term was a nightmare but now i have taken roughly 15 years of aging away, adrenals are back on line, thyroid is back on line, my brain is working well, the gut is imo the hardest to heal fully. i had multiple exposure to mercury from fillings, vaccines and environmental exposure.
one thing i have noticed is that the adult chelators (people who chelate) seem to sing the same tune of 'i am really sure things will get better, so and so has improved'. but it never quite seems to pan out into the silver bullet that everyone thinks it will be. then they disappear and we are not really sure of what the results are. there are a few stars like jeff clark who have gone the distance, but he seems to be the exception and not the rule.
dmsa imo is the most toxic of the chelators. i keep hearing story after story about people that did not do well at all on dmsa. this is also corroborated by dr. buttar. dmps on the surface seems scarier but it seems to work best for people. note: dmps was never intended to be used intravenously. it was formulated for oral use only. ask the manufacturer heyl pharmaceuticals.
if you can tolerate saunas and keep yourself hydrated, if you do enough saunas you can make a huge dent in the problem. there is a guy who sells Far-Infrared-Sauna saunas who more or less cured himself, but it was grueling saunas twice a day for 3 years. this obviously eliminates any stress on the liver and kidneys as long as you stay properly hydrated.
and there is also the strategy of keeping the fillings in and just properly opening up your elimination organs to handle whatever gets released.
people do recover with fillings in and without them. people seem to find very creative ways to heal across the whole gamut of therapies. most of the information is on curezone, but sometimes it is hidden away (in short little posts by people with little or no ego).
if you could find a way to just get your gall bladder working that could be the end of your troubles.