They can be caused by a number of different things...Antibiotics, tight clothes, sitting around in damp workout clothes (or a wet bathing suit), and eating a lot of sweets are some common causes, but sometimes they seem to appear for no particular reason.

I agree yeast is very sneaky you might feel find and you go to doctor and told you have a yeast infection. Diflucan os a great pill for yeast infection. When im given that med I go to the herbal store and purchase acidphillous that is that ingredient that is found in yogrut. It helped me