It sounds almost certainly that its a condition known as 'Idiopathic Head Tremor'. It is known in English Bulldogs, Dobermanns and more recently it has been recorded in Cavalier King Charles, that does not exclude other breeds no one really knows when a dog is taken to vet with it so there are no serious records.
It has been extensively studied by neurologists in the US and the cause remains unknown, although a hereditory cause is suspected.
There is rarely a pattern but generally the bouts are much more frequent in young dogs, it can start at around 5 months and bouts can be several times per day or even per hour or you can get one bout a month. The bouts can last for a few seconds or many mins.
The condition might start to decrease at any age from about 2 onwards and bouts usually become occasional occurrences as the dog gets older. There are no known adverse effects but it can be extremely distressing for an owner untill they know what it is.
steph 2
>We now give her a small amount of chocolate, when I say small I mean 3 or 4 maltesers or a couple of cubes of choc, or a small bite of mars,<
I don't now who told you to try food but very often giving a bit of kibble will stop it with a lot of dogs, some neurologists suggest it could be a muscular problem but its only guesswork, they do not know. But yes small bits of food seem to be the commonest way of stopping it in many dogs which are affected.
BUT-You should NEVER give a dog human chocolate of ANY kind, it can cause problems, is life threatening and can kill, I think its something in the cocoa.
I have posted this subject separately as plenty people know more about the dangers of chocolate then me.