What Causes Extended Periods,abdominal Pain And Menstrual Cramps After Having Unsafe Sex?

Hi, I m 18. My boyfriend and I have been having unprotected sex for about 4 months. Last month I started noticing changes in My body. For one My periods went from last 7days to 4 maybe 5 . I ve been discharging a lot and having pains in My stomach. Like menstral cramps but. Not as terrible .I started My period April 3rd & on the 11th we had sex something has come up and I was wondering if there s any possibility I could be pregnant. It s too soon for tests but I need to know soon