I'm doing heavy metal chelation right now. The tests showed lead levels through the roof and also cadmium, aluminium, etc.
One friend said these levels were enough to cancel out my immunity and enable the chronic parasites (and low level candida) to go on and on. He said when the heavy metals are chelated, immunity would be restored and then antimicrobial would work better.
I don't think any chelation done with health food store supplements is going to get you anywhere - not if you're really serious about it.
If I were you, I'd find a good naturopathic doctor, get the levels tested (Doctor's Data lab) and then let the specialist conceive a protocol according to which metals are highest. This can be done with combination of oral, IV chelation, or even with patches (DMPS).
I am getting calcium EDTA in intraveinous chelation - and I assure you the metals are coming out. But it's no piknik. I get IV glutathione and vitamins and minerals too to support the detox process. It's a lot of work for the body.
Also, doctors who supervise my chelation told me it is not enough to chelate metals out of the bones, tissues, brain - but to make sure that your detox pathways are clear and highly functional - so the metals are excreted properly out of your system and not just recirculated and redeposited elsewhere.