[racinghamster]

Right, you have recently made a change to the bedding or substrate? Can you say more specifically what this is? Mice can suffer from stress mites, allergy and if they start to scratch to obsess, it can become severe, so the symptoms and behaviour you describe need addressing right now to try and reverse this.

1. What substrate are you using now and what were you using previously?
2. What nesting material do they use?
3. What diet are they fed on and has this changed recently or always been the same?
4. What age are the mice?

Come back to me when you can. x