If you still have mercury fillings, just make sure you're not taking anything that'll pull the mercury out of the fillings like any mercury chelators (e.g. alpha lipoic acid, cilantro, EDTA, DMSA, DMPS, etc).
And be careful about mercury testing, specifically the "challenge" test. It has the potential to make things worse in some cases.
I've been down the mercury road, if you have questions.
Mercury is also illusive, but a hair test might be beneficial as a general test. It could shed some light on multiple issues, heavy metals, mineral levels, mineral transport issues, etc.