Is it possible to have herpes on one tonsil? Tonsil is swollen and has 5 tiny canker sore like ulcers. Didn't have blisters. Lymph nodes are swollen.

Herpes in the mouth. Well depending on 'what happened' recently I would include herpes as a possibility. Herpes ulcers generally form at the site where they invaded. If you had receptive oral sex, then in theory it would be possible. The best way to find out is to see an ID doctor who could take a culture to prove or disprove this theory. There are other causes for an ulcer back there, so I do recommend getting seen.