my right thumb has been twitching since five days off and on. Two days prior to the twitching, I had constantly pushed a button on my mobile in order to get it working with the help of my right thumb. Should the twitching have subsided by now? Can injury cause this sort of twitching?
Note: My thumb visibly jumps.
The pinched nerve in your neck could most likely be the cause. I think it's the medial nerve that goes from your thumb and some other fingers (not pinky) to your neck and shoulder.
It is possible that the pinched nerve is the cause of the thumb twitching. If it persists and you are bothered by it, you can opt to consult a neurologist.