Strange but serious question

So me and my bf broke up and I slept with two people (he slept with someone else too) and everything was okay. But just a few weeks ago we got back together and we started having sex again and I just got a UTI or maybe an STI. I have a doctors appointment tomorrow but I'm wondering did I get it because of him? I got a UTI before with him but every other guy I've been with before him and the other two guys after we broke up I felt fine. He's the first guy I ever got a UTI with. I've NEVER gotten one with anyone else.  I don't want to bash him. But could he just not be clean or is it me? Answers?