I am sure what I have experienced is not the same as you must cope
with, but I had involuntary spasms for a couple of years, especially
in my left hand, arm, shoulder, plus very bad "benign essential
tremor". Fortunately, I eventually figured out (as my doctors
apparently did not) that it was being caused by medication, which I
have managed to get off. But meanwhile, I got very good at bracing
my hands against each other and solid surfaces to do everything. I
put bricks or other solid objects beside my work so I would have a
place to brace my hands as needed.
I also was fortunate enough to find that I didn't shake quite as bad
when I was concentrating really hard.