Shedding? Fur slipping? :/

Hi
I've had two chinchillas for around three years now, and there's been a weird development with one of them. She appears to be shedding, but its gone on for too long at this point. My instant thought was fur pulling/fur slipping, but it's happening around her head too, where she can't reach. She's not losing fur, the fur regrows, she just seems to be eternally shedding. I'm so confused...