that you contracted something in your mouth from the provider, if you didn't do any kissing or oral.
Could it be herpes? Sure it could be, but if it is you probably already had the virus as the majority of the population is infected with hsv1. And if you did get it from the girl, I don't believe that symptoms would show up that quickly.
It also could be canker sores, or mouth trauma (bit your tongue, or cheek or something, or a small cut from food etc.) Could be a lot of things. Go see your doctor