Sorry to hear about the chemical sensitivities. They are tough. They seem to add years to the detox process. My heart really goes out to those folks.
They almost always tolerate small 5mg DMPS doses every 6 or 8 hours better than DMSA or just ALA. Of course you'll want to take generous doses of vitamin C and E but folks with MCS often struggle to tolerate them. If you are one, ask Josette, one of the moderators of Yahoo Frequent Dose Chelation. She's suffered with MCS and is gradually improving.
Check AC's Amalgam Illness book around p 40, the section on liver support. Try to understand the concept of slowing down Phase I as well as providing support for the various Phase II processes.
Have you found types of liver support that have been helpful?
Taking more generous doses of minerals especially selenium caused my relatively mild MCS to go away in the years before detox. I can't say I've heard that frequently in the groups but that was my experience.