Any traumatic lesions in the mouth would be immediately adjacent to your wisdom teeth, or at sites of other obvious injury. There are viral respiratory infections that cause sores in the mouth, notably a thing called Coxsackie virus, and others. In theory, I suppose it could be perrpes, but that sounds unlikely--but you say nothing about your sexual exposures, STD risk, etc.
Your school nurse may be a fine person, but if your symptoms persist I suggest you see a more experienced health care provider.
Regards-- HHH, MD
I forgot to mention..
I am an 18 year old female. And the last time I had any sexual contact was a little over a week ago in which I engaged in unprotected oral sex with a guy I've known for over five years. He has been tested, was clean, and didn't have any weird marks on him or anything.
That's important information. The timing is right for an oral herpes infection. See a health care provider who is knowledgeable about STDs, such as your local health department STD clinic. Take the guy with you for an exam at the same time.
Good luck-- HHH, MD