Heavy metals are one of the major 'body burdens' that James Wilson writes about. I had my mercury Amalgams removed and worked on mercury chelation (using a very gentle but for me effective approach called Field Control Therapy - FCT). But I did this only when I was strong enough to handle it. It took me about a year and a half to build up my general health and my adrenals after I came down with a chronic illness to be strong enough for this process.
I would suggest doing a lot of reading about mercury and Amalgam replacement before taking action. There's a lot of information on the web. This is one area where it really pays to be very careful and make good choices. I'd strongly recommend working with a skilled practitioner if and when you decide to remove your mercury. What you don't want is for it to be moved around your body, causing even more trouble.
As is the case with most detoxification I got worse before I got better from the mercury removal. But then I got considerably better afterwards. It wasn't my whole answer but it was a valuable part.