Talk to your physician. There may be medical professionals in your area that specialize in treating musicians...the larger the metropolitan area the better the chance to find one.

For example, at Sentara Neurology Specialists located at Sentara Norfolk General Hospital, Norfolk, VA there is a neurologist that "works with artists to prevent and treat problems resulting from musical performance such as overuse injuries, nerve problems, and involuntary muscle spasms." In Minneapolis, there is a musicians' clinic, the Courage Kenny Rehabilitation Clinic. Similarly, there is The Performing Arts Clinic, a part of the Brigham and Women's Hospital in Boston.

Of course, neurologists who treat tremors should be a first stop. Until then, the universal admonition is to avoid stress and limit smoking and caffeine. On the plus side, some consider small amounts of alcohol beverages a help. :rolleyes:

If you find meaningful help let us know. I have a tremor in my fret hand and in the past couple weeks I think it has started to affect my practice. At least, that's what I blame some of my slow playing on... :D