Poor Harley is sooo itchy

I have brushed, furmitated and brushed some more - I see nothing!! No fleas, no mites, no dandruff - he eats duck and potatoe food which keeps his skin moist (from the oil in the duck).
He seems so sad and depressed he is mopey - even my husband mentioned that he seems to have gotten old in the past 2 days

We are going to the vet tomorrow at 9:30 - my regular vet isn't available I hope I like this other vet. I'm thinking it is seasonal allergies??
He keeps rubbing against the furniture to rub his back!
Poor baby
Randy and Harley