Its also good for you to know, it may not be food related at all
But even if its not, feeding a grain and potato free food could help keep the symptoms from getting severe.
But if its not food related, you will prob have to consider allergy testing.
However, just dry itchy skin and infected ears doesnt always point toward allergy.
Ear infection can be from too much hair in ears, or moisture from baths, swimming, etc.
And dry itchy skin can simply be dry skin
From the weather, or whatever just like people get dry skin.
I hope your able to figure out what it is.
Unfortunatly i have 2 dogs with allergy/ skin problems. Its a lifelong battle.