Did he recently start this or has he done it all his life? I think some dogs just have a nervous shiver, just as my dog has a nervous whine. If he started it recently and your regular vet can't find anything wrong with him, I suppose you could ask him to refer you to a specialist.
Never trust a tall dwarf... he's lying about something.
I have a 9 yr old Beagle who also shivers but that didn't start until December. Not to say this is what's wrong with your dog, but my dog was diagnosed with lymphoma 1/8/08. I've read that a dog only shivers when they are cold or in pain. 9 is not very old for a Beagle so I'm wondering if he is in pain, although he doesn't act like it. Hope this helps.