Give her some pedialite. No joke! It works for dehydration and diarreha. It doesn't have to be any particular flavor, but for the benefit of the cat, make it as bland as possible, they don't like strawberry, or vanilla, if they have it, try banana, or something like that.

If it keeps up much longer, you really should get her to the doctor, when this sets in, they can dehydrate rather quickly, so if she develops any other symptoms, get her in right away. Hope this helps, good luck.

 You can give it milk,and that's it.