Infections or cancer

I had sex and after that I took p2 after 42 hours, I was in my period then. After that I had sex three more times with the same person, the second time I experienced burning after urination and abdominal pain , the third time I was bloodied it went on for some days it wasn’t very heavy but it gave me cause for alarm. Two days later I had very painful back ache so I went to the hospital and a test was conducted in my urine, but the doctor said he saw nothing. That there was no bacteria growth after 24 hours so he diagnosed ulcer cause I do have ulcer. So sometime later I had sex again but I didn’t not see blood that day but the next day like after 24 hours (I have not taken p2 then) it was just spotting on the tissue I use to clean myself after I pee . It was red and thick at first then it was light red like pink. I took p2 26hours after sex but whenever I pee I still see stain on my tissue. So I don’t understand what’s going on.