It sounds like you might have a Candida problem going on. Get a few books about it. Trowbridge has a good one, so does Crook. There's lots of information in those books about the diet plan, supplements to strengthen immune system, anti-fungals, and complementary treatment to address related problems (such as allergies). It's not something that will be 'cured' so much as managed, IMO.
The books have info and lists of questions to help you decide if this is an issue for you. Since this is more of a syndrome, it is just one piece of the puzzle that needs to be addressed. The books go into a lot more detail.