About 3 months ago I was walking into a building and missed a small step up and fell hitting my left knee on the solid cement floor. Once I got up I could barely walk. I immediately elevated it and iced it. There was pain in the side and behind the knee for about a week. eventually it went away. In the past day, the problem has surfaced. My calf feels like the after affects of a "Charlie horse". Behind my knee and the left side of the knee have a dull pain. I can't straighten my leg out completely. When I sit for a while and get up I can hardly walk. After walking a few minutes it gets better. I am using small amounts of ibuprofen because of stomach concerns, icing and elevating.