I had my period then a few days later I started bleeding/spotting. I was having really bad abdominal pain and really bad odor. What does this mean?

Could have been. How long ago was it that you had sex last? Usually there is a small sack that gets discharged during an early miscarriage.

This happened two months ago I but I had sex while on my period and after I had gotten off

Well then there is really no telling. It could have been one but doubtfully. You wouldn't get that bad of cramps just from pushing out a one or two day fertilized egg.