Nebo does that every now and then. He'll shake his head a bit, scratch at one ear, then hold that ear funny. I always look in there and it looks perfectly fine, his ears have never even been dirty. In an hour or so he has stopped doing it and is fine. He has done this several times and I have never figured out why, it is not often though. I hope it is the same for Sherman. The only thing I could think of is if maybe a foxtail or some type of weed got in his ear, or maybe a bug (tick?).