what happens in Vegas apparently doesn't stay there

Hey guys so I had sex with this guy I met in Vegas. We vibed a lot. And I asked him beforehand if he was clean to make sure just in case. Anyway we didn't use a condom tbh.. which was stupid but I trusted him. And basically I'm not close to my period but I peed a day later and there was a spot of blood. None in my white underwear though. Not to mention I had a fishy smell but no itchiness or difference in discharge or anything like that could have been because my lifestylre was not the best. I just need to know what this blood is. What should I do?!