Is it an STD?

Okay so, it may be just from anxiety but I'm really freaking out. About a week ago I gave head to a guy who has had sex with a few different girls. Anyways a week later I had pus in the back of my throat, tonsil stone. I popped it by scratching and it came back. There's no pain or redness but it's freakin me Out that I might have gotten something