I'd also check that she's up to date with her worming. Kittens have an unfortunate habit of eating things that they shouldn't, so if she looks at all droopy & can't keep water down...you'll have to go to the Vet.
You could try going back to basics for a couple of days to give her tum a rest...scrambled egg, white fish or chicken are a good sore tum food. I've got a little one at the moment who's off his food, and thank goodness tonight I got him to try some cod at last, they're a worry aren't they!