Are you eating your green, leafy vegetables? B12 deficiency is often signified by numbness in the hands and arms. Back when I was teen away from home for the first time I ate nothing but hamburgers and fries - I would wake up with my arms numb from the elbows to my fingers such that I would have to flop them around using my shoulder muscles (I was out in the wilderness working on a seismograph crew), it all went away when I got home and ate my vegetables again. While I was on the crew, one of my jobs was driller's aid where I would screw and unscrew the pipes as the drilling got deeper and deeper - eventually the thumb on my left hand started shrieking with pain; it was a form of tendonitus and I got a cortisone shot to clear it up. It could be some form of that. There is also repetitive stress syndrome which could just be another name for tendonitus.
