Your dog may have allergies to airborne particles as they will often shake the head,lick the paws, scratch the ears. Most culprits are grass, rag weed, pollen and dust. Your vet can do allergy tests to determine the cause. Since the dog is shaking the head a lot you will need to watch for an aural hematoma which is when the blood vessel's in the ear break and the ear flap fills with blood. This would need surgery. I am going to direct you to a site on airborne allergies and aural hematoma. I would suggest yo get the dog in for a check up for allergies. Generally benadryl is prescribed to help with the itch.