Sore throat after oral sex?

So I’ve noticed this since I started hooking up with people in high school, but every time I give a blowjob my tonsils get swollen and I have white spots on them for a few days after. This stopped for a while, because I started gurgling with mouthwash immediately after. But it just happened again because I ran out of mouthwash and wasn’t able to do my routine. As far as I know I’ve never had an std...so what’s up? Does this happen to anyone else?