Mouses toes turning brown

Question
I have a wild mouse I raised from an infant (her name is Natasha!) She is now four and a half years old. She has lots of energy and does not appear to be in pain (though I know prey animals don't show their vulnerability) She has what appears to be a huge brown scab on one foot,(hematoma?)  and all of the rest of her toes on all of her feet are turning brown. They are enlarging as well. She has also lost a significant amount of weight in these past 6 months, though I would say her energy and vitality have increased. I am concerned that her toes are dying. I am not sure what to do. Do you have any idea what this might be and how I can help her?  

Let me know if you have any questions.  Thanks.

Answer
Please send photos.  I can have some medical people from the rat community take a look.

In fact. If you are on Facebook I want to do one better. I will add you to a group with some really good medical people including vet techs and a vet. That way there can be questions and answers.

On Facebook I am Ratasha MouseRat.

https://www.facebook.com/natasha.mouserat

I run the group Rats and Mice are Awesome (Facebook name only Rats are Awesome), which you should join:

https://www.facebook.com/groups/RatsandMiceareAwesome/

Friend me and I will put you in a different, medical group, as well.

What is your history with the little mouse? What is her story?

Very sorry for the delay :( :(

Squeaks,

Natasha