Im by no means experienced with head shakers but some years ago my boy used to headshake quite violently during summer and on very cold misty days. The vet wasn't sure if it was headshaking because of pollen or neuralgia. Anyway after some googling I read that someone had had some success using Hilton Herbs' Freeway (think it was called something else in those days) but I used that and have used it intermittently ever since and he's virtually stopped. May be coincidence but thought id just come on here and give it a mention.