Maybe he got allergies from prior dog food. You would probably save money with people food. One pound of pasta hydrated makes 2.5 lbs of food. And you can mix in a can of tuna into it, and some vegies.
Funny story decades ago. A friend of ours had her older mother stay over. Eda went out for a while. When she came home, her mother mentioned, “Eda, those Swedish meatballs in the fridge were delicious” “Mom, that was Alpo you ate”.
Obviously, things were of a much higher quality back then when the cost was no object for people, even entry level. You know, over time they made packages smaller and items cheaper less quality to match falling wages.