Yes it could be, but those symptoms ring more true to an environmental allergy than a food one.
I would put her back on a very simple chicken and rice or chicken and corn based diet designed specifically for large breed puppies. The ones that stand out to me are Pro Plan Large Breed Puppy and NutriSource Large Breed Puppy. Leave her on that through the winter to see if the symptoms subside. If they calm down in the winter, this may indicate an environmental allergy. It may take a while to determine what the cause of the itching is. Possibly another full year to see if the symptoms arise again during summer.
Do you by chance live in the South? Environmental allergies are rampant down here because of our humid climate.
