First you have to stop eating all fish and possibly stop all supplements made from the sea.
Second you have to remove all the mercury amalgams.

The body is a natural chelator and will remove the mercury slowly on its own. ALA alpha lipoic acid, available at any vitamin supply place is probably the safest, cheapest chelator that crosses the blood brain barrier but should not be taken until 3 months after Amalgam removal. Meat is also a natural chelator.

Roky

One of the safest and most effective mercury chelation (detox) protocols is the one by Andrew Hall Cutler. Two forums are devoted to using his protocol alone and a forum I belong to has many on there using it and finding it effective, so word is spreading. Particuarly those who have found other protocols ineffective or even harmful to them. Some being made worse!

This protocol is becoming more widely known and more doctors are finding out about it and applying it to their mercury toxic patients. It is a protocol that is designed to move mercury in a safe manner, rather than mobilising it wildly as many other protocols can do which can increase the risk for possible damage and the mercury ending up in more sensitive tissue (even the brain).

I would recommend you start with Andy's protocol, but only after all Amalgams have been removed. I agree with Roky that ALA (alpha lipoic acid) should not be used until 3 months post last Amalgam removal. Your body/blood/tissue levels MUST be reduced beforehand (usually with DMSA). The body can naturally do this to some extent on its own, but takes a longer time and is usually much more uncomfortable. You can speed this process up and increase the elimination of mercury with DMSA (available online). This can be used to reduce the body, blood/tissue levels. It is advised that it be used according to Andrew's instructions. This can be crucial.

The advised protocol is taking DMSA every 4 hours around the clock (yes even throughout the night). You do this for about 3 days straight (or up to a week if you wish). You then take a break from it for about the same amount of time you spent on it (or more if you need to). E.g. 3 days on, 3 days off. Or if you want, 3 days on, 7 days off. That is just an example. So long as you do it for more than 2 days but no longer than a week or so.

The dosage is usually about 25 mg - 50 mg, but many find this too much to start and have to split the dose up. Some take as low as 6 mg, but many find 12 mg is fine. You can increase the dose later as tolerated.

I would suggest you do a google search online about the Andy Cutler protocol. He has written a book called "Amalgam Illness, Diagnosis and Treatment" which is excellent and takes you through everything about mercury. What it does, where it goes, what symptoms a person can get, how to help your symptoms, what to take and how to remove mercury effectively and safely without causing more damage along the way.

I hope this is of some help.