I suggest the possibility that heavy metals have been in your body for years, but you didn't develop the worst symptoms until you did something to cause a yeast overgrowth. This is only guesswork though since I don't know your history in detail.
Cutler should be helpful with lead too. Of course, EDTA would be best for lead, but it doesn't work so well with mercury.
As I'm sure you know, Cutler does recommend DMSA first before ALA, and I think it is probably the better way to go. I do know that there are people who use ALA only, but I haven't seen anybody write about how successful ALA-only is. That would be a good question for the chelating boards.
Cilantro/chlorella helped me a lot. I think Cutler is better for somebody who is new to chelating because everything is laid out for them. Cilantro is better for people who have more experience with the whole chelating thing (and won't do things like eat too much cilantro or take it haphazardly).
Perhaps you could try a method for 3 days and see how you react. Your reaction (or lack of reaction) would give an important clue as to whether or not heavy metals are the cause of your trouble.