She's been scratching more than often. And has developed those black dirt like spots on her belku. They're not flea poops. Did the check for the that.
I said "handling." After years in the vet pharm industry, I have some anecdotal knowledge about how the food is handled, ie sanitary. Hills, Purina, and Eukanuba transport their food in their own trucks. They do not ship their product in trucks used to transport other items, that could have had something bug infested in it in the last shipment. So even if there is fillers, at least it's corn and not bugs.I also have to disagree with the hills, eukanuba and purina recommendations..their food contains many fillers, little actual meat, lots of common allergens, and is just not a well balanced diet.
My dog scratches when on corn. I don't believe orijen has that though..so maybe she just needs a different protein source. If the salmon doesn't do it you could try lamb and rice. If that still does not fix it maybe try a grain free brand.