Sounds like her internal chemistry is not agreeing with what she's eating. (just like certain foods may give a human gas). She may be having a reaction to a particular ingredient in the food, an allergy of sorts. Admittedly, this is hard to determine and harder to narrow down, but keep in mind two things. 1st- an animal can have a reaction to a food even if it's the BEST FOOD AVAILABLE due to a single ingredient. and 2nd- It will take a while for it to clear out of the system and settle down to normal.