Saska started to doing the head shake and the vet advised me that she has a build up of ear wax, so every couple of weeks I have to put ear cleaning fluid into her ears, it appears to have done the trick, good luck I hope you find the cause.
Sam's been doing the same thing quite recently. I've checked her ear, too. No signs of a visible infection, but as we're going to the vet on Monday (heartworm+booster+flea stuff), I'll let you know what she says.
Sam had a really bad ear infection when we first got her but there were obvious signs of infection. She had a very dirty ear and it took me and 2 vet techs to hold her down while the vet cleaned it and put drops in. It was obviously very sensitive..
Sometimes you can't see the "gunk" but when you clean the ears with the purple stuff, it comes out !! The purple stuff, is great....... just follow the regime she has on her website.....
He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion.