Any food suggestions for Bulldog w/allergies

[thg812]

Hello fellow Bulldog owners. Our bulldog Ottis is 2 years old & he is our 2nd Bulldog. As you all know, trying to figure out their allergies is difficult. We thought we found the best grain free food for him(Natural Balance, Fish/sweet potato) but recently it does not seem to be helping. He will eat & immediately start rubbing his head/face up against whatever he can. He has very dry skin & sheds a ton. If anyone has any suggestions for food or ..whatever can help, it would be much appreciated.
Thanks, Tom & Ottis