Hi I Hit My Knee On A Hitch A Few

Hi I hit my knee on a hitch a few months ago. It hurt at the time but I went on and had a little bruise and it hurt for about a week. Well know a few months later I can bend my knee for a few mins and got to straight it out and it hurts or when im asleep with it bent and I straight it out it hurts. I also have a small bump on it right in the middle of my knee cap