Bad Cramping

So me and my partner had unprotected sex during my high and peak of my ovulation (8th and 10th Nov) I'm currently experiencing bad cramping to the point it makes me feel nauseous. Now I'm thinking its probably my period but I've never experienced cramps like this before they are normally fine with the help of pain killers at times. What fo you think this could be? I am thinking its just gonn be a very heavy and bad period but any other advice would be great! :)