Hello. I certainly am not vet, but it sounds like perhaps something she ate is causing this, similar to how we can get food poisoning. Maybe it has something to do with her change of food that day, but since she didn't eat much of it I am thinking that is just coincidence and she probably got a hold of something else.
I would take her to the vet today if you can. Its already been over a full 24 hours and doesn't seem to be getting much better yet.
I am so sorry she is sick! Good Luck! |