What Causes Vaginal Bleeding And Stomach Pain During Intercourse?

Hi, I am 26 years old and I have always had pretty regular periods. I have also had three pregnancies... all three of which i knew i was pregnant before I actually missed a period... the first two were the result of a bad relationship with my ex-husband and were aborted. however the third one resulted in my beautiful 15 month old son. his father and i have been together for 3 years and we have a great relationship... not sure if that is relevant... anyway, after having my son i tried using a copper iud but eventually had to have it removed because it was causing too much pain... especially during intercourse. however, the gynecologist who removed it said that i just had a small uteris and i am very petite and it just wasn't right for me. eventhough i had pain and sometimes bloating during and after sex with the iud, i never had bleeding. last month, i had that same feeling that i had the other three times that i might be pregnant. we had been using condoms after the removal of the iud... but this time (we had had a few drinks) and didnt use a condom at first. my husband didnt "finish" until he put the condom on, but i have heard that it is still possible to get pregnant. however, my period came right on time so i didnt think much more about it. it ended about a week and a half ago. 3 days ago we had sex and we used a condom like usual. however, i started bleeding during sex. it was dark and very clotted. i didnt really have much pain at first but my stomach has started hurting... its not really the same as usual menstrual cramps but im not sure how to describe it. i am still passing dark clots, especially when i urinate. i am worried and i dont know what this could be or what i should do