Hi i started having some pain too the back of myleg at he knee when I lifted my leg a few days ago with no known injury,drove about 10 hrs yesterday getting out of car veery 2 hrs and walking,I am now having severe pain if I lift or bend that leg and even worse if I put my knee on something and let my weight bear on the knee,the pain is n the back,there is no visible s/s,no warmth or swelling .It does not hurt to touch,bear wt or walk