Please take her to the vet. Is she overweight? I haven't posted about what we are going through right now [will fill in details later] but we have allowed Toto to gain wayyy too much weight. She began to act exactly the way you described. The first time she yelped we immediately rushed her to our vet. Her little sternum isn't long enough to accommodate the weight and she has five ribs which have become "disconnected" at the bottom. Looking at the X-rays was horrifying and I will never, ever forgive myself for allowing this to happen. We are desperately trying to get some weight off her but it's difficult because she doesn't feel like walking. Sorry this was long but I was shocked at your description because it's identical to what has happened with Toto. Please keep us updated!!
__________________ "The difference between genius and stupidity is that genius has limits." -- Albert Einstein |