wound on Fancy mice

Question
I need help identifying what caused a wound on my mouse Cookie.  The wound is located at the back rump area.  It is about the size of a pencil eraser.  A complete perfectly shaped circle that is down to the meat.  The wound has a little white hard object that has increased in size.  The white is about the size of a pencil point but not pointed more rounded. Cookie has had the wound for 5 days now.  I called the vet and he said it was a bite wound.  I separated my two females,even though I've never seen them fight during the 8 months we have had them.  I am putting Neosporin/plus pain ointment on it.  Haven't noticed any improvement.  Please help if you have any suggestions.   Thank you so much.

Answer
If they have never fought before it seems strange they would start now. I don't think its a bite wound as they often don't appear in a perfect circle. It could be something like a wart or an infection. If you could send me a photo I may be able to help more. Without seeing it, it would be difficult for myself or a vet to diagnose it properly.

I haven't heard of Neosporin but you can continue to use it if it is suitable for small animals.

Does the wound cause her discomfort? I would take her to the vet so he can give her the right treatment.

I wouldn't separate them unless you think it's contagious as mice are social creatures.

I hope she recovers soon, please feel free to ask any more questions.