Is it normal that i get unbareable pain after sex sometimes?

Sometimes when I have sex, if I feel it going too deep, afterwards I get this horrific pain in my lower abdomen, it feels like a really horrible period pain, it lasts around 20 minutes and it slowly fades away. It's the worst pain I have ever felt, its so bad it makes me just lay and cry the whole time. Does anyone else get this? And can tell me what it is?