What Causes Involuntary Movements In Hands?

Hello, I am a student nurse that works in a clinic, and I have started to notice that while I try to hold the thermometer in a patients mouth that my hand steadily shakes. Plus, sometimes when I'm holding a pen trying to write it can get very shaky. Almost like the muscles are having spasms. When I pull my hand up like I'm waving and hold it, it will also shake like it's experiencing muscle spasms. It's only my right hand. I have recently been experiencing numbness from my right shoulder to my finger tips. One night it felt so weird that I guess instinctively I kept holding my arm straight up in the air because it seemed to help it from feeling as weird. Is this anything to worry about?