One of my chickens does that but only when shes trying to brood. And she hasn't been laying, is that a problem? Oh well, back to you. Do you have multiple chickens?
Have you tried milk? That should give the kittie the runs(not to be gross). I've had 4 cats in all, but 2 at the moment. They are VERY expensive animals! Hope the milk helps(if you haven't used it already).