Hi. Im 8 months pregnant. My boyfriend and I had sex a half hour ago and now I keep feeling my stomach tighten up like a fist almost every 3 minutes and it feels like a little pressure in my back, what should I do.

He could have been a little too energetic too close to your cervix. After all, you have only one month to go. Get checked out by your obygyn. It doesn't hurt to be extra careful during intercourse about now.