this is a common allergy, b/c cats can become allergic to anything they are exposed too often and as you too will have found out
chicken is in almost all the cat foods.....they put a
chicken 'base' in even some fish diets. so one has to red the labels very carefully.
GRAINS are also a huge culprit, I sure agree!!!!
I will also add some to your lists
GOOD FOODS. Natures Variety. Tiki, and EVO for a few
DRY Foods if you must....