I've been having it for a few months and finally asked my midwife. She said the prostaglandins in the semen can help thin your cervix but can also just be uncomfortable. To prevent the cramping she said use a condom or have him pull out to finish.
As far as contracting after sex, contractions are caused by oxitocen, which also causes orgasms. So you're more likely to contact afterward if you climax. BUT they're probably just Braxton hicks. Lay down and drunk done water. If you get more than four in an hour, call your Dr/midwife/local labor and delivery.
Its like a throbbing feeling
I get the worst side a aches ever!
I actually get abdominal pains too, but mine are also like vaginal cramps..it's super weird and uncomfortable. I assumed it was normal but I need to ask my dr about it.
I'm the same way but it's more towards my cervix