Have you had allergy tests done? Megan used to lick her feet and her tush and her ears smelled funky and she wouldn't let you touch them. I had her on several different premium foods and nothing changed. WE finally had allergy tests done and found out she is allergic to fish, milk and rice.
I went back over the foods I've fed her since she was a puppy and they have all contained those ingredients.
I now home cook and use Pinnacle duck and potato for their kibble and she is like a brand new dog! She isn't licking anything anymore and I can rub her ears for as long as I want now
I would highly recommend having allergy tests done just to see which direction you should go.