The prehensile thumb allows human beings to attempt fine motor skills, and evolved from our forerunner Homo Habilis. It consists of three bones, and its movement is controlled by 8 muscles (4 in the hand, 4 in the forearm).
Yesterday, it began with a tenderness in the joint, then spread to a sore feeling all throughout the finger, and ended with pain whenever I moved the digit. Thinking it was a sprain, I've attempted to immobilize it, but was not as successful as I hoped. Each time I needed to type or pick up items or merely tug at something, I could feel a twinge in the hand and sometimes through the forearm (which taught me that those 4 muscles in the forearm are definitely attached to my thumb). A doctor friend of mine has told me to take painkillers and have it x-rayed today. It may need to be splintered for a few days to a few weeks.
I've had to be extra careful holding anything in my left hand, and even putting on clothes (struggled with the bra snap and buttons) is ridiculously painful. And being overly imaginative, I have begun to imagine what it would be like if it needs to be amputated. Of course, it's more likely to be wrapped up for a few weeks, and then will need regular exercise to get it back to normal speed.
A few hours later from writing the above: I've come back from the doctor and blood tests and xrays. The doctor says it is not a sprain and that it's some infection. He's asked me about insect bites, but I can't remember any recent nibble. I've spent P3000 for medication that is supposed to stop it and turn my thumb back to normal, one hopes. So far, the pain is less than it was, but the swelling is still noticeable.