*pop* is never what you want to hear coming from your knee (Read 533 times)

Yesterday at the very end, literally the last minute, of my easy five mile run, i heard a *pop* in me knee. Not just my knee cap; the pain that came with the pop is behind my knee cap, running on the inside of my leg. I walked it off, didn't push myself the rest of the day, figured some RICE would be a good idea. Today, that area hurts walking up and down stairs and it bothered me on my short 3 mile treadmill run. Any ideas what this could be? It's not swelling (although its hard to tell because I have chubby knees), but it is bothering me. Some more RICE won't hurt, and I'll take tomorrow off running, but I was just curious if anyone has ever had a similar problem as this? Anyone know what could be hurting me?

A very little bit...it still twinges a little today, but only going up and down stairs, so I guess rest is all that it needs!