I bought a comb to groom my shepherd with and get out all of the under coat. Lots has come out since I started combing her. I have noticed alot lately that she has really been scratching and biting at herself. I thought it might be a food allergy so I switched to Wellness super5mix. She loves the food, but I noticed after I combed her and had loads of hair from the undercoat come out with the comb, that she now has little white flakes. Could that be what is causing her to scratch and bite? I have had to washed and groomed at petco, and wondered if maybe they didnt get all the shampoo out since she had so much undercoat. Anyone know any good shampoo's to use on her for here at home?