I think sosick is right get some advice from someone trained and experienced in the area of heavy metal detox. I would also add be wary of DMSA it can make things feel worse. You could try Algin which is supposed to mop up mercury in the gut. I have found this helpful for me.

Plus whats your diet like? You might want to try an anti candida diet and see if things improve with that. Bex on this forum is knowledgable about that.