You know there's someone else out here that knows more than I do, but I think I'd just try massaging it for her. Keep a close eye on her and jot down when she's doing it and for how long - like you're already doing. If it increases in any way - then I'd call the vet. Maybe it's her food, or just growing pains. She doesn't make any noise when she does it, right? Well I hope she's ok and that someone else can offer some suggestions/answers. Good Luck! I'll be watching to see what happens.
