Umbilical cord-related issue?

I think that my baby's umbilical cord might have gotten rubbed off by her diaper accidentally. I know it's supposed to fall off on its own. How can I tell that everything's okay. It's a little reddish and scabbish. When I look inside her belly on it does seem a little greenish, slightly. That would be an infection, but is it possible to seem like it is infected when it's not?