I had a normal period for october then i had sex & my period came two weeks early & was light & only lasted three days. could i be pregnant?

Possible..: Yes, this is a possibility. In that case get a pregnancy test done in order to find out with certainty. If not pregnant, I would wait until next period and if it happens again then out would need to see GYN provider in order to get evaluated . If you are having vaginal discharge and pelvic pain then you should be seen ASAP to check for possible infection.