Earlier today I was leaving a store and as I walked I experienced a sudden, severe pain (enough to catch my breath) in my right knee. I was just walking on even ground. No apparent injury, just the pain. I continued on and this happened twice more before I got to my car. It seemed that if I didn t allow my knee to straighten completely when walking I was okay, but if it straightened, I d again experience a sudden, severe pain. This has happened many times since, but now happens if my knee is slightly bent or straight. The stabbing pain, and now the throbbing seems to be right under my patella. I m stumped and a little concerned about walking for fear of experiencing this pain again. I might describe it as something catching somewhere under my patella, but I m not sure that s quite it. There s no swelling, no bruising, no misalignment.