Cat's stomachs can get upset switching food. Suppose to do it slowly. Rocky's stomach got upset and she got the runs. Our vet said to hold food for a bit and then feed Baby food, meat only (Gerber 2nd foods turkey is what we used) and then start adding in the new food again. It worked. However my cat is not a kitten so I don't know if they would recommend the same. You might just call your vet and ask if that is ok to do. Mine just told me over the phone.