A Pain In My ......Knees

Okay, okay...I can assure you that I'm not falling apart but some days it sure seems like it. I have this new pain and, if anyone out there knows what it might be, please clue me in.
I have a pain in both of my knees. It is much sharper on the right than the left and is located right smack under the middle of my patella (knee cap). It doesn't hurt to walk but it does hurt when bending my knees. I climb the stairs with a moderate amout of discomfort but this discomfort turns to pain when descending the stairs or bending my knees to squat. It literally takes my breath away for a second because it is sharp and fast in its onset but disappears when I stop bending it. I didn't bump it, twist it or do anything to it other than my normal exercise. I first noticed it doing the leg press machine at the YMCA a few days ago and it's progresively worsened so much that I skipped that machine today and also skipped karate today. Does this sound familiar to anyone? I'm certian it isn't M.S. related because it's not that kind of pain.