Is my degu getting old or sick?

Question

My male degu Nybbie is about 3 years old. In the last 2 weeks or so he's drastically lost weight. Now he is a skeleton with fur, and I'm scared. His sister fro the sae litter, Chyrrip, is just fine. She's chubby and active, with shiny fur. However, Nybbie is tired, sleeps alost all day long, only picks at his food (azuri blocks, chinchilla pellets, Timothy hay and fresh veggies) no matter what kind of treat I offer. Also, sometimes when he stands up he'll lose his balance and stumble. I've noticed he hardly runs in his wheel, he'll still use it everyday, but mostly just to walk or sit in. He doesn't climb as often as usual, either, and has fallen fro the bars of the cage onto his nest-mound, which he hasn't spent much time on for awhile either. He used to build onto his ound everyday. His eyes are shiny and bright, his fur is sort of less shiny, but he doesn't respond to seeing his sister the way he used to. He used to purr, chitter, squeal, buck and wag his tail. Is he just old?

Answer 1

I think he might be sick. You should take him to the vet right away.