What Is The Treatment For Swollen Middle Finger?

One morning last week, i woke up to my middle finger on my right hand swelling up. It hurt to bend it, and to use it picking things up, but i can move it, so i know its not broken.
It feels as though i have a bruise on the left side of my knuckle, but can't see any bruising, and it hurts to move it?
The swelling still hasn't gone down, and is still painful to use. I know i haven't knocked it etc, help? Lauren.