Well from the papers I read, only ~33% of the mercury ALA picks up is excreted. With DMSA about 65% of the mercury it binds to is excreted. DMPS is like 85%. SO thats why DMSA would lessen your symtpoms because it helps excrete the mercury that ALA picks up but doesn't remove.

You will get some redistribution if you stop, but if you can't handle it there is no other choice. For the nausea some peppermint or ginger tea would be good...but I would probably just stop if I was you and wait a day or two and start again with maybe 1/3 the dose of ALA.