hello, I have had an achey r knee after I finished a 13.1 race in mid June , no injury but I really pushed it. , started physical therapy. stiffness and tightness in the back of knee has prohibited full extension of knee without pain. I starte stretching and strengthening exercises. last week i was walking a little biyt fast to catch a bus , it was getting tighter and tighter and it popped and buckled. Went to ER and am in brace and crutches. xray revealed lots of swelling around knee. I can weight bear, but it is still swollen in back of knee and tight. I have been icing a elevating for a week.