I guess I must press particularly hard on my keyboard with my index finger, or it's the most used digit; but, it has been painful for a couple of days. Notably, I cut my nails short a couple of days ago. So, I suspect there's some connection, at least to some degree.

Not knowing what this could be, I did a search online and found RSI - Repetitive Stress Syndrome. It's a bit like carpal tunnel syndrome, whereby non-ergonomic repetitive use causes the injury.

There is nothing new about Carpal Tunnel Syndrome. Anyone working on an assembly line or typing 8 hours a day can tell you that.

What's different is that Carpal Tunnel Syndrome used to be connected almost solely with one's work. A typist, an assembler, a seamstress.