Yeast infection.
Canestan - 7 day version is best.
Also, avoid all simple carbs for awhile. Anything the body reads as white sugar in a short period of time - like sugary cereals, cakes, donuts, cookies, things like that - white breads, mashed potatoes, etc. Stick to complex carbs instead until this passes. Hope it helps. Best of luck.
PS - I would never use bar soap in that area. Try a glycerin brand like Pears (sold in most Supervalu or supermarkets) that are not perfumy.
It's too bad you have to deal with this at your age, but it sounds like you've got a typical yeast infection. Any woman can get them at any time for no reason at all, so you needn't be embarrassed about it. There are over the counter meds you can try, like Monistat, and that often helps get rid of it. Otherwise you'll have to get a prescription for something stronger from a doctor. Do a search here for it and you'll find TONS of women just like yourself with the same problem. Good luck.