@ Meghann P,
When you have a dog with a sensitive stomach, in my experience I have found it best to avoid potatoes (white and sweet)
Where your dog is under the care of a veterinarian it would probably be best to go by his recommendations for now. Keep the food bland, maybe stay with the boiled chicken and rice for a few days, then gradually introduce the kibble in with the mix, it might take a couple of weeks.
Some info on by-products:
More Nonsense from Holistic Vets about Commercial Therapeutic Diets
and:
https://www.mspca.org/angell_services/choosing-the-right-diet-for-your-pet/
