Since the licking has stopped on this food, I would think allergies are a possibility. The only way to know is to do an elimination diet. Have you tried Natural Balance Duck and Potato? Then after 2-3 months, you can slowly add other ingredients in to see if you are correct about the chicken.
While switching up ingredients, please be careful. Variety is fine but they should not be exposed to every protein and every grain source available because if there is a serious food intolerance someday and you have to go to something novel, that will be impossible.
This just happened to me with Ellie...I gave her too much variety in her carbohydrates and now I am regretting it. Her nutritionist said I have boxed myself it.
