Ok, i am coming here because i currently have no health care and cannot afford to go to a doctor and I can't find anything on the internet. About 2 months ago I noticed sharp pain behind my knee when I bent my leg after it had been extended a while or extended it after it had been bent for a while. I just avoided keeping my leg in one position for too long and thought i had just pulled something. Only now it hurts to bend my leg when I walk, and going upstairs. The only time i have relief is when my leg is bent at a certain angle. I have been reduced to limping around because of the pain is at times almost unbearable. Sitting, standing and walking have become a chore. I am an 18 almost 19 year old female.