Did the vet check for ear mites? Infection in the ears? look in the ear and see if there is dark dirt like substance. This would be ear mites. Smell ear if a musty Oder then probably an infection. You can use 50%alcohol 50%peroxide as an ear was after baths or swimming. With ears that lay flat upon the head it traps water or dampness in the ear. Causing ear infections. Check with vet again if infected.
My Dog Keeps Shaking His Body And Attempting To Scratch The Left Side Of His Head With Anything He Can Find. What Could It Be?
Possibly ear mites
They sell car seats but they are expensive. They also have seatbelt attachments that hook to your dogs harness.