Suggest Treatment For Bruised And Swollen Knuckles After Injury

Hi, today at school I was goofing around before class and accidentally wacked my left hand off of the cement wall. My ring and middle knuckles are extremely swollen, bruised and thriving at the touch. I can't fully straighten my fingers or make a strong full fist. Do you know what's wrong or what the treatment could be ?? I am a 16 year old girl.