My guinea pig has a scab on her bottom back, help!?

My guinea pig,popcorn, is a girl. She has a little tiny bald spot on her backside which looks like a . When you look closely it's not a hole, it sorta looks like a loose piece of skin. I have had her since last October 2010 and I always thought it was sorta like a poop hole but when you look closely like I said it is sorta of a scab or loose skin that won't fall off. Help I don't know what to do, is there any solution that doesn't include taking her to the vet? I don't want to overthink things and Pay alot of money for no reason. Thanks and sorry for the long description:)