Fur Clumps?

[Plymouthchins]

Hi I used to own a breeding pair of **** beige chins a few years ago I had to sell them due to circumstances however as it has changed again I now have 5 chinchillas who I all adore. 2 females came from a petshop and 3 (2 females and 1 male) came from a local lady. The 2 females from the pet shop seemed in a bad way and they had clumps of fur hanging out from their backs... I would pluck it out of them but then the next day I would find more laying on the cage floor and stucking out again. Neither of them have any bald patches and ive never seen them aggressive with each other? They are in my room and ive never heard anything over night either I decided to mix all the females together in a very large cage and they all got on great (obvi after keeping cages together and letting them meet in neutral ground and put them all into a new cage) never heard any aggression between the 4 of them but they now also have clumps of few sticking out.. do I have a serial fur chewer?? There is always fur laying on the bottom of the cage? I have separated them off again until I can work out whos causing this...but any advice would be good as to what they are up to