What Is The Treatment For Enlarged And Sore Knuckle?

I smashed my index finger knuckle bone ( the one at the base of the finger) with a thorn from a locust tree a few days ago. At first I thought nothing of it, but today the knuckle is swollen and I can't move my finger and there is a lot of pain. there is no redness around the tiny punture wound, which is all healed now. The knuckle is enlarged and sore. I soaked the hand in epson salt in hot water, but after an hour and a half it feels much worse. What do you think is going on?