Sex before period or early pregnancy?

I had sex with my bf yesterday and during sex (in the missionary position) I got sharp cramps in my lower abdomen. It happened a few times n I felt uncomfortable almost the whole time. We tried other positions and missionary was the only one that didn't feel as uncomfortable. Doggy I think is what felt the most uncomfortable. I have also smoked a few days ago or so, and I threw up 3 times and I had a headache n I was dizzy. I also had Arby's 3 hrs before, so maybe I got food poisoning or something. Idk. I have smoked since then and I haven't thrown up. Also the next day, I felt nauseous in the morning a bit n my stomach hurt. N all that day I had like a nervous butterfly feeling. The sides of my boobs and my nipples have been sore since probably the 3rd or 4th. Could it be because I should start within a few days to a week? Or could I be pregnant?