HELP!! My hamster is having bald, scaly, itchy patches on her underside/haunches....no mites that I can see...?

I noticed these the other day. I've seen her scratch at them just a couple times....but they look dry and scaly. I looked for mites, which was my first thought, and I dont or cant see any little black dots or bugs. I dont know if mites are just really hard to see or if this is something worse. I had a snake who had mites and those were very easily visable.....dont know if its the same or not though. My question being, could she have mites and I just cant see them? Or does this sound like something worse?