I don't know much about mice but I know with guinea pigs (which hide their illnesses until it is almost too late), that as long as food and water are both going in and coming out and behavior is "normal" (not too hyper, not too sluggish, not making strange noises or movements, or strange discharge from the nose, mouth, ears, etc.) then it probably is not an emergency. If Squeaky does have any of the above problems, I'd try to convince the vet that it is an emergency. It sounds like she's doing better and I hope she stays that way.