Chinchilla matted fur??

Hi all, I really need some help here. This is my female chinchilla who’s I’ve been told is around 4 years old. I’ve had her since she was 1 and she was rescued by a lady who found her left in a carrier somewhere. Her fur was kinda gross but her owner said it was because she hadn’t had a bath in a while. So after giving her baths she got nice and fluffy and healthy looking.

Starting a couple months ago I noticed her fur slowly turn mated and almost chewed down? But I’m NEVER seen her chew it in my life and she takes dust baths.. she doesn’t seem to do anytning to it but as the days go on it keeps getting worse. I thought maybe she was depressed and I got her a lot of toys recently and also let her play in my room so it’s a new environment and stuff.

I got her to be friends with my other female chinchilla named Chia but sadly chia hated her and hates all chinchillas and then being friends never worked. I still try but they get mad. So I was left with 2 separate ones, they can still see each other when they play because I seperated the ferret nation cage into two. When one goes out the other can see and so she isn’t completely alone... it’s weird because she was totally fine for so long. Any guidance on what could be wrong or if I should go to the vet?