How long have you been feeding that? Have you tried switching to see if it's something in that food?
I have an allergy ridden dog as well. The issues never completely go away when they're as bad as mine. I transitioned to raw. Every kibble I tried didn't help. He still gets his morning zyrtec and he still needs a second dose in the spring, but for the most part it's under control.
"i can explain it to you, but i can't understand it for you."