Had A Really Bad Fall On A Cement Floor 3

Had a really bad fall on a cement floor 3 weeks ago. Badly bruised knee - the bruising is gone now but the swelling is still there and the knee feels so tight, like a band is around it. Also, a lump on the left side of the knee, like a buildup of fluid. I have been elevating the leg and using a heating pad. How long can I expect this to be like this.