It's possible you're anemic. Do you ever feel dizzy?
I've been anemic most of my life ( lack of iron) my hands would shake alot and I'd feel dizzy. You can get over the counter vitamins for it. It helped me a lot.
My left leg sometimes (only rarely) shakes for some reason. <br />
Some blood tests I had for an unrelated issue showed I was borderline anemic. That might be something to look into.
Are you on any medication?
Zoloft used to give me tremors. Exactly like the way you described. It was frustrating.