Raw fed dogs can be allergic to different meat proteins

it's possible to be allergic to chicken, fish, beef or lamb. Or any combination of them

Sometimes it's worth trying a protein they haven't encountered.
With my extremely allergic Afghan X it was
any meat protein. All his problems disappeared when in desperation I bought the Stella McCartney vegetarian dog food which was peanut and soy based IIRC
He also had major ear problems, but that turned out to be a polyp on a long stalk which irritated his ear every time he moved. He given a general anaesthetic for tooth cleaning and I requested they have a proper look in his ears at the same time, as they were talking ear ablation. One snip and it was cured!
His allergies continued though when the Stella McCartney food was discontinued. I put him on piriton in the end as the steroid treatment wasn't worth the side effects.