Please don't avoid seeing the doctor. IF it is a yeast infection, only a doctor can diagnose you and give you the proper treatment. There are over-the-counter meds but without knowing for sure that's what you have, you should not use those meds. It could be a lot of things so the doctor who prescribed the birth control should be contacted since it could be related.
If you were both truly virgins, the risk of having an STD is very low, but not impossible.