Sometimes, my left and right thumb twitches. Its an involuntary action and couldnt be controlled. It happens for not more than 20seconds. My hands doesnt shake but my thumbs do. The other day, I wrote my notes for my class for more than 2-3 hrs. The next day morning, I couldnt write in middle of the class. I couldnt hold my pen with strength. I felt weak in my fingers. I couldnt make a proper fist. What does this mean? Should I consult a doctor?