Not a UTI

So I keep having a burning after i pee (not while I’m peeing just after I pee), it makes me feel like I have to pee all the time, it started after me and my boyfriend did stuff (with a condom), it’s been a month since then and it still does it every once in a while, I have been checked for a UTI by my primary doctor and at the ER since then and they all said it’s not a UTI so i don’t know what’s it is or what to to to stop it and it’s annoying when I can’t sleep because I have ti pee every few minutes