I don't know why the doctor gave you an antiviral either, if HPV was suspected? As mentioned, there is no routine testing for oral HPV, may visually see a wart that can be HPV 6, 11, that is non cancerous, and occurs in other areas too, but to my knowledge, antivirals are not the course of treatment. There are over 150 different types of HPV, with about 15 of them being high risk to possibly cause cancer, and it's mainly HPV-16, that may cause oropharynx cancer, mainly tonsil, base of tongue, in 1% of the people exposed to it, and the majority of people's bodies fight off the disease within two years. HPV oropharynx cancer, doesn't usually present itself with an ulcer, unlike tobacco related cancer or pre-cancer does, but that doesn't mean a co-infections or disease can't be present, and most times it can be something other than cancer. Anyway, antivirals are for viral infections like HSV-1, HSV-2, and anti-fungal for Candisis like thrush, a fungal infection, and antibiotics are for bacterial infections, others too, usually the first course of treatment most doctors prescribe to patients presenting with head and neck symptoms like most of us were, for some reasons, since it may resolve whatever it is, but I'm not a doctor. I would see an ENT, preferably one with cancer experience.

Good luck with everything.