Sounds like he just tore a little skin. You're talking about a very sensitive spot that tears easily. It should heal just fine on its own. If it does not seem to be healing after a while, go to your ob-gyn. She might be able to give you a cream to speed healing.

In the future, you might want to get some lubrication from the store. Anytime you start feeling dry and raw, stop and add some. That will lessen your chances of getting cut or getting sore.