Hmm, I'm not sure exactly what kind of pain you're experiencing but I hope you find some relief. That does not sound fun.
I'm wondering if it's from the suction effect the cup has. When I first used mine and took it out, I didn't break the seal and it felt like I going to turn myself inside out! It was quite unpleasant. Now, like CA, I just make sure to pinch the bottom and start to take it out at a bit of an angle. It even helps to push one side of the wall in with a finger to break the seal. If that makes sense.
Good luck! I hope you find a solution. I had a few bumps in the road with mine, but I absolutely love it now.
"Live, more than your neighbors. Unleash yourself upon the world and go places. Go now! Giggle. Know. Laugh. And bark the the moon like the wild dog that you are!" - Jon Blais