Not sure if this is related. Around 4 years before the whole problem started, I was diagnosed with severe depression and was put on antidepressants. 2 months or 1 month before my right hand just dropped down, I changed antidepressants from SSRIs to an older tri-cyclic one (don't remember the name), which I didn't tolerate well. Could that be somehow related?

The only potential, clear pattern I see in my health history, would be gluten intolerance or it. B 12 deficiency. I saw a doctor once for chronic fatigue when I was 16, and got a huge depression years later.