Suffering From Pain And Bruise Due To An External Injury

I was tripped at a roller skating rink and went down really hard. All the impact of my fall went on my left knee cap. When I got up and skated off the rink, it felt like fire-y pain and I almost couldn t skate off. It was like that for 30 more minutes while I sat and rested. It s the next day now, and the swelling has gone away, but it s still extremely sensitive to touch and hurts when I bend my leg. However, there is only a small green outline on where I fell and in the middle of it is some red and purple. Will it full on bruise? How long until it heals?