Embarrassing question 😰

So for a couple months now after sex and sometimes during, I get this really horrible burning sensation. We put it down to an STI (I did have Chlamydia, my partner and I were both treated for it , but I was tested recently and it came back negative) so now that's ruled out I thought it might possibly be a reaction to his semen, but (tmi) we had sex today and he made sure he pulled out right before he came and everything seemed to be fine until I went to the toilet to pee, and it burned like crazy!

If anyone has had any similar experiences, any advice would be greatly appreciated. (I will be seeing a doc, but first hand experience is always somewhat relaxing) im 12 weeks and 5 days