3 weeks ago I was pratting about with a chin-up bar, which I running upto then swinging a few feet in front of it. One of occasion I tried to turn whilst in mid-air but i ended up clipping my knee on the edge of a radiator. I hit the radiator near the edge of my knee cap, on the inner side. It really killed for at least 5 mins, where I couldn't move or anything. For at least the next 7 days, I was walking with a limp and climbing stairs was painful. Since then it gradually got better, however it's not fully recovered. Sometimes now when I'm sitting on a chair where my knee is bent it starts to hurt. When I'm driving and have to change gears using a clutch it can hurt. There's no obvious bruising or lumps when looking at the knee. Any idea what the problem could be? I'm tryin not to put any excessive stress on my knee, but I am running 3 mile runs every few days. I hope it's nothing serious or long term, if i knew 3 weeks later i'd still be suffering then I'd have gone to A&E when it happened.