I have heard of quite a few people being "cured" of Candida overgrowth after sufficient heavy metal chelation. Heavy metal toxicity, especially mercury, suppresses the immune system, allowing Candida to take over.
Look into heavy metal toxicity and Andrew Hall Cutler's books and protocol -- the SAFEST way to do chelation. (Other methods can do much more harm than good.)
Chelation itself tends to exacerbate yeast for some, but after awhile it ceases to be a problem...