Originally Posted by John Nixon III
. . . The finger in the relaxed position now stays this way. I can move it to a straight position; but only manually.
My right pointer fingertip is like that, my doc said it's "mallet finger". I have rheumatoid so mine comes and goes, for most folks it's a repetitive motion or sports injury that can heal completely. It used to be called "baseball finger" since baseball players got from jamming their finger on the ball but now with so many hunt 'n' peck, one-finger typers, it's become very common among computer users. You should see an ortho to make sure it's not something that might get worse.
There is an old fashioned splint treatment for mallet finger; take a paper clip, place it under the bent fingertip so it's straightened out and put a bandaid (lightly) around it to hold it in place. With some OTC anti inflammatories (aleve, advil), it should work pretty quick, in a day or two.