One possibility is that you are developing diabetes, so check that out (probably a fasting blood glucose test will be necessary). Minimise coffee, and start slowly switching to decaf.
Avoid sugary drinks, especially those with High Fructose Corn Syrup, or artificial sweeteners, like Aspartame (enter them in the searchbar at www.mercola.com). Use stevia, xylitol, (health food stores) or a LITTLE honey, or raw sugar.
85% of people are suggestible, to some degree, so you could either seek professional hypnotherapy, or hypnosisdownloads.com has on about controlling essential tremor.