[Sheenagirl]

Well this probably isn't going to help you much because there are so many reasons:

Yes, fillers in dog food can cause allergies (fillers such as corn, soy and wheat gluten).
Ear mites
Moisture in the ear
Ticks
Ear infections (signs: heat, infection, odor, drainage, wet, sticky hair around the ear.
Foreign object deep in the ear.

You might end up taking your girl to the vet so he can look deeper into the ear.
Good luck, hope she is better real soon.