I guarantee you the heartburn is from the 6grams of garlic. Well, not guarantee but I'm pretty sure. I wouldn't use chelex, why not order DMSA, cilantro, ALA separately as they are easy to get? I dont think the EDTA is necessary unless you have lead issues.
Also, the fatigue can be due to a lots of things so dont let a little fatigue scare you. For one thing, I would supplement with a multimineral as chelators deplete the body's minerals, especially EDTA. That could be the sole cause (or not) of the fatigue.