It probably is thrush, which is no big deal, but let this small lesson keep you from having to learn a much bigger one. Herpes is a lifetime illness or even worse HIV. Unless your in a mono relationship, birth control is not enough.(As you are a teen, it has been known to happen that girls have lied about being on birth control in order to get pregnant. I don't know why but in some teen circles it is considered cool to have a baby.)