What Causes Movement In Abdomen After Sex?

I never had sex in my life but I have a boyfriend and we slept together some times. I ve been feeling strange these days and I feel like I am pregnant.I don t have a missed period or any change of weight. I just feel like there is something moving in my belly and i feel sick many times per day, specially when I eat. I would like to know were can I do a blood test. If a need a referral from my GP to do that... Thnaks