It sounds like you have a yeast infection, and a bad one. When you have a yeast infection sex irritates it and makes it worse. They sell kits at stores that can test if its a yeast infection or some other infection and you can buy over the counter medication once you know if its a yeast infection or not.
you can treat a yeast infection with anti fungal cream, and if it doesnt work then you should seek medical advice....as its probably not what it is.
i would recomend going to the doc, there are other things out there thta have all the same sighns of a yeast infection.