When you have heavy metal toxicity everything is more difficult, overall if that metal is mercury as it really damage your body and all enzymatic processes. The chelator agents are substances that bind strong enough with the toxic metals, basically sulphur foods so that your body can eliminate them on your urine or poop, but there are many many factor that accelarate or delay or totally stop the toxic elimination. DMAS, DMPS, ALA some some of the most popular agents or substances use to remove metals from your body but is has to be monitorized by and specialist or you really have to educate a lot on this topic as it is heavy stuff and if done in the wrong way can really harm you badly. My advise is first of all get your candida and your colon going and in the mean time try to find a naturopathic doctor that knows a lot about chelation, educate your self on it, by one book that is very good on chelation his author is ANDREW CUTLER, get into the autism forums and read as much as you can on chelation.
Also super important remove Amalgams from your mouth but remember that you have to get a dentist especialized in safe removal otherwise
you will get sicker as the Amalgams vapor and debris will fall on your throat and into digestive system poisoning you badly.