Well i had sex with my boyfriend and we dont know if he precum inside of me. after a day i started bleeding but not a lot. then my stomach was hurting?

Infection? Pregnant?: Abnormal vaginal bleeding (between menstrual periods) and unexplained abdominal pain both need professional medical evaluation. If you're pregnant, it could be related to that. If not, there is concern about pelvic inflammatory disease (PID), a common complication of chlamydia or gonorrhea (if at risk for STD). See a doctor ASAP, for sure within a day or two. Good luck!