PLEASE HELP

While I was at the beach I had sex in a pool with my guy friend and of course he didn't wear a condom and he didn't even get off in me. But I had my period 2 weeks later and the day I started I threw up and was cramping so bad and now 2 weeks later I just felt sick all of a sudden and threw up in the middle of the day. I have also been feeling really weird. Maybe it's from where I'm worrying that I'm pregnant but I don't know. I'm really scared that I could still be pregnant even though I had my period. Opinions please?