What Causes Stinging Pain In Middle Finger?

Hi. All of a sudden tonight I got a horrible shooting/stinging pain in my middle finger. I thought maybe I'd gotten a splinter or something but my mom and i looked and there was nothing there. It went away for a little while but is back again.

It's this one spot in the middle of my middle finger joint. It stings/burns so badly if anything touches it and if I extend my finger at all (or sometimes curl my finger inwards). But it only hurts in that one spot.

What could it be?