i have been on birth controll for almost 3 years, recently i have become really inconsistent about taking the pill and have pretty much stoped taking it completely. i have had unprotected sex between my last period which was at the end of january and now, my concern is that i have started to bleed blackish brown, which i thought was my period, but im not supposed to start my period untill the end of feb and it is only the 18th? any ideas about what could be wrong?