about 3 months ago i fell over during and banged the top part of my knee on the corner of my door, there was a light mark where i had hit it and it was moderately painful but there was no crack or pop. I got up, rubbed it and shrugged it off. about 20 minutes later, whilst sitting down my knee got stiff so i moved it forward/up (as if to put my feet up) and there was a loud cracking sound about half way and this continued every time it got stiff but the cracking sound had reduced after the 4th day. About 2 weeks later my knee became very painful for no apparent reason and hurt every time it cracked, this cleared up about 10 days later. What i was left with was a tender feeling knee that was very warm and would occasionally crack but whenever it cracked i could feel a strange sensation as if rubbing your knuckles together before it cracked and provided some relief. This was when i started to get worried. To this day it continues to grind before cracking but after it cracks it doesnt do it again until it becomes stiff, it is instead replaced with a clicking sound. I have full range of motion and no pain when it cracks but it only cracks when sat down and i extend my legs upward whilst sitting and it sometimes feels like it is catching on something behind the knee but isnt painful. On top of this my knee has a kind of dull tingly pain on top of the knee cap about halfway through the day and it gets really warm. By the end of the day my knee feels really tired. Any possible insight on this would be greatly appreciated.