I am a 36 year old active stay at home mom. Two days ago I went down my stairs and noticed my right knee making a popping sound. It did not hurt and I had not had any recent injuries. The next day I noticed that I had a slight dull pain and as the day went on the knee became a little swollen on the outside. The swollen area is just under and to the outside of the knee cap. It does not hurt to walk but if I am on the floor and get up, the knee definitely seems a little week and of course I still have a dull pain. FYI: I do run 3 miles a day, about 3 to 4 times per week. The odd part is that I did not run last week because we were on vacation. So, not sure if it will go away or if I should see a doctor. Thanks for your help. Wanda