It could be focal seizures causing the tremoring.
Unlike grand mal seizures only a part of the body responds. It all depends on where in the brain the 'electrical storm' takes place.
High red blood cell numbers often indicates the dog is dehydrated but can also indicate uncommon diseases that cause an over production of red blood cells from the bone marrow.
Here are links to some of the possible problems
http://www.vetinfo.com/dblood.html#Polycythemia%20vera%20and%20other%20possibilities%20when
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=545994
http://forums.cvm.missouri.edu/cenbb/viewtopic.php?t=771&view=previous&sid=dae7c6f54181cb666b4411c9ca672d46
This site is the best I've found on epilepsy causes and treatments
http://www.canine-epilepsy-guardian-angels.com/site_map.htm
But it sounds to me like its the high red blood cell count that might be triggering the tremoring due to difficulty in getting enough oxygen to the brain.
I suggest seeing a veterinary specialist in internal medicine or neurology for more help than your vet can give. This site may help you find one
http://www.acvim.org/Specialist/Search.aspx
Hope this helps you!
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