I can't straighten my middle finger, or make it touch my palm. It's a bit swollen, but not so much that it should be stopping it from bending properly. It doesn't hurt much, except to feel a bit bruised around the middle joint. This has now happened several times to both my middle fingers (they recover on their own after about a month) and to one of my ring fingers, and feels like it's starting in my little finger too. It just happens spontaneously, no accidents or trauma to the joints.
I went to the doctor last time it happened and was referred for arthritis tests, but they found nothing. And the fact that the joints don't feel warm or too painful suggests to me that it's not arthritis.