I've got a pain in the back of my knee. It doesn't hurt while walking and hurts slightly while running on level ground, but I get a sharp pain running up hill. This came on recently after a long hill workout on Thursday almost a week ago. Normally I would back off and just rest it. Actually, I'm running NY in less than two weeks, so I'm into my taper, but I'm still worried that it won't heal by the day of the race. I did about 13 miles 3 days ago and the pain got slightly worse throughout the run and it also caused my calf to tighten, which bothered my more than the pain behind the knee. Does anyone have any ideas as to what this is? Ligament? Tendonitis? Is this something that will heal before the marathon? Any treatment advice?