Bleeding on pill?

Hey guys, Ive been on birth control for a little over 2 years now. Last week I had some bleeding after a little bit of cramping just a few days after my period. I haven't had sex since 2 heavy periods before this (not spotting) so i knew that it couldn't be implantation bleeding (I souldnt be ovulating on the pill anyway) and the next day I had a sharp pulsing pain on my lower left abdominal area. Im not sure whats going on and Ive had some weird symptoms;kind of gassy, and slight cramping every now and then. Could this be a cyst? Could I be pregnanat? Or do you think the blood was just left over from my last period?