Odd hand pain

The last couple of times I picked up a small-diameter pen, I got an odd pain around where the thumb joins the hand. The same thing happened this evening when I gripped a not-light bowl to wash it.

Making a note of this in case it's the start of something vile. I'll want to know when it started. Now I think I'll go research tendonitis and carpal tunnel (noooo! not that!). Eeeuw, it could be arthritis at the site where I broke my wrist a jillion years ago. Or possibly I just strained something when I sat down at the piano after a long hiatus.