confused, pls help!!!

ive been on Minesse since the beginning of the year, i had intercourse about 2 months ago but got my period (a week early) otherwise everything was normal. Then October had intercourse and the next day i had brown discharge and 2 days later i got my period (a week early) it lasted for 3 days and then i had the brown and black discharge again and then bleeding for one day and the next only discharge. this has never happened to me before. i had intercourse during that time when i thought i was finished with my period and then a week after my period. For the past few days ive been feeling a heavy sensation at the bottom of my stomach and have been having problems with my indigestive system. Im not sure what could be causing all this, but could i be pregnant???