Amanda,
Call him or the NP back and tell them your concerns. I'm not a doctor but I if used the "differential diagnosis" guidelines, I would be treating you for an infection also. You can always get an second opinion from another ENT. Try to find one with cancer experience and not one who spends all of his time sticking tubes in kids ears (not that yours does - but there are sub specialties within specialties). A comprehensive cancer center would be able to rule out cancer. I still don't think you have cancer but I have seen enough children at the CCC, while I was in treatment, to know that young people do get it. I have to admit though, I don't recall meeting any with oral cancer.

What makes you think that you have oral cancer? It could be something as simple as plain old tonsillitus. You need to give us more information if you want us to "second guess" what's going on. Like what kind of antibiotics? Maybe he switched you to a really powerful one? Like Cipro?

Have other close family members had cancer? Do people smoke in your household? Do you live next door to an oil refinery? At 19, you should be out enjoying your life and not worrying about cancer. Where does all of this fear about cancer come from?

"Second guess" is the best we can do over the internet. Our primary mission is actually to help survivors with post treatment issues, mainly by sharing our experiences. Secondary would be patient advocacy.