Any idea?

I was having sex one night with my boyfriend, I was on top facing him. It was feeling really good and once we both finished I had this sudden feeling. It felt like I instantly got a UTI/bladder infection. Like bad symptoms, it felt like I had to pee so bad and it was like an achy burning pain. I took a hot shower and drank some cranberry juice and was basically fine. It's happened a couple times like that but not that bad. Any ideas of what that could be? Or if someone's experienced the same thing? Also been having lots more period clots, I thought that was strange too. Thank you in advance.