What Causes A Brown Discharge In Menstruation?

Okay...So I m 14 years old... My boyfriend and I have unprotected sex... I think I may be pregnant but I don t know... around the time I was suppose to get my period I had this brown discharge that look so much like mud and then a few days later I had light pink streaks like blood when I wiped (they only happened once) and then today 10 days later I m having a white cum colored discharge