I'm very, very worried for Jupiter. She has Stopped eating and she's gone very skinny. When I hold her she feels so weak. I use Wagg hamster gerbil mouse munch but I don't think the food has anything to do with it as my other mice are all very healthy. She also has injuries on both of her ears, the top of her head and her neck is hairless and swollen. She does live with her sister, but I've never known them to fight.
Please help me, what should I do? I really don't want to lose her!