If he can tolerate barley, maybe look into 4Health salmon and potato? I really can't remember if it has chicken in it or not, nor can I remember if there are grains in it other than barley, but Chloe does quite well on it. And since mid-price to me is, well, cheap, it is only about $30 for a 30lb bag, I believe, maybe a bit more.
~*~ Cynder ~*~ Abrams ~*~
Daddy's Girl Lab/Spaniel muttly and Momma's Boy Chesapeake Bay Retriever
Home Away from Home: Chloe, Gracie, Cooper (dogs), Apollo (cat)