Information on White Dog Shaker Syndrome

I have a 3 year old Yorkshire Terrier that was diagnosed with White Dog Shaky Syndrome 9 months ago. He has been on Dexamethasone(.25mg per day now) and Meclazine(only past month) along with Lactulose and DMG (dimethylglycine)and Hepato Support capsules for his liver, and a fresh slice on Ginger twice a day. He walks but always shaky, falls down quite often and is permanently tilted to the right because of all his "episodes". These episodes can vary in number and duration but exist every day. When episodes occur, he turns over and over, his eyes move rapidly back and forth and he knows now to just lay flat until it passes. Most times I just hold him until it's over. Are there any other alternative medicines that may decrease his episodes?