Hi, I am on birth control. I had a normal, regular period October 26th-30th. I started a new pack of active pills on the 2nd. I had sex on the 10th. Started bleeding on the 13th, 14th, and 15th. It stopped. I had sex the 16th and 17th. I am now experiencing cramps, headaches, bloating, a bit of nausea, gas, and diarrhea. Is this PMS or could I be pregnant? How soon will I know?