A few people report an allergic reaction to taking even 10mg doses of DMPS several times per day with plenty of Vit C and E--Cutler protocol.
Your reaction seems typical of taking too much of a heavy metal chelator!
I chose Cutler's method for myself and my very sensitive girl friend so you know what I'd say.
I've used DMSA along with LA since I seem to have mostly a lead and cadmium problem. When my female friend wanted to start--after getting Amalgams removed--I felt DMPS was likely a better fit for her even though I had plenty of DMSA to give to her. Instead I paid for her doctor visit and the first bottle of DMPS. It has worked better for her than DMSA although she can tolerate an occasional round with DMSA + LA.
Don't forget to take plenty of antioxidants. Mg, Zn and some adrenal support are often helpful. So much more could be said.