Its burns when i pee lol?

Well I was seein my ex and we have a baby so never use condems , anyways while I was seein her it kinda burned down there and felt swollen and sore, kids burned a lil when I peed but she been gone a month and it feels back to normal, but still Burns a lil sometimes, no discharge or anything, not ant extreme pain just kinda uncomfortable, I have had a lot of partners and got tested last year and I was clean, I was with her alot unprotected and never burned, then we split, later I got tested and then we got back together, and she's the only person I've been with since I got tested