Google idiopathic head bobbing or tremor. Although it is seen most frequently
in boxers, dobermans and bulldogs (I had a bulldog that had it from about the age of 4 on) in can happen in other breeds. If it is only the head, and most importantly, if your dog is otherwise lucid (able to respond to his name, can walk around etc) during the episodes it may be this syndrome. If so, pheno will do nothing, as no actual seizure activity is taking place in the brain.