Have you checked his ears? Use a piece of gauze wrapped around your finger and swipe around, gently, inside. If his ears are inflammed, smelly or you see brown gunk on the gauze you need to see the vet. Even if you don't see or smell anything I would have the vet check his ears if there is excessive scratching. I really don't remember any puppy scratching more than normal so I don't know about the skin growing theory. (I have never heard that before!) Chewing on his feet often and itchy ears make me wonder about allergies which would be awful for a young puppy. Salmon oil is not going to help allergies and I would be very careful giving any supplements to a young puppy. JMHO.