Very painful menstrual cramps?

I've had these bad cramps lately with my period. It gets so bad that I don't wanna get up from my bed and even makes me skip work because of it. The pain starts at the lower abdomen, then radiates to mid thighs. I do work out, so I don't understand why it's this painful. I feel better when I sit down, but it only helps a little bit. It also comes in waves of pain too. I literally feel like someone is squeezing my uterus. Pain pills help, but they take forever to work. What should I do?