My Guinea Pig Is Acting Strange When He Poops. Help?

My guinea pig is acting very strange while he is pooping this morning. He kind of hops and then sits and then sticks his backside out and poops. Then he sticks his head into his stomach and eats it. I know this part is normal for guinea pigs, but this morning he is doing a lot of poops. I must have cleaned up nearly 30 stools in the last fifteen minutes. He isn't making a sound when he does it so I don't think he is in pain, and he is eating in between doing this. Is the crawling and hopping part normal? I have never noticed him doing this before and I don't know if I should be worried or not. I'm also worried about him sticking his backside out. Any advice would be much appreciated.