My girl scratched and nibbled exactly the way you described, turns out she is allergic to grains in the dog food, i have switched her to grain free food and she is not scratching anymore, she is also allergic to chicken not sure why but now we avoid that too
__________________
Reebok border collie rescue M.A.D
Ace's carbon copy "Xerox" ATCHc border collie
Risin sun maximum overdrive "Driver" ATCHc Border collie
zaushower "Jackpot" P.I.T (pup in training) GSD