Answers plsss???

Heyy, ladiessss. I need some advice or help! Two days ago my bf and I had sex. Immediately when we were done. I had this tightening in my uterus, almost like bolts of lightening and I threw up. Yesterday the pain wasn’t as severe but I could still feel it every move I made. Now today my lower abdomen is tightening almost like a gassy feeling but I don’t have to use the restroom. Im 5 days away from my cycle. Can someone tell me what I may be experiencing?