I fall over every time it snows/is icy, so when my knee first gave the odd 'owwww' moment (usually if I twisted it slightly) I put it down to that. But now it's been iffy for a number of weeks. It aches like a bastard when I walk upstairs, in the way that actually lifting my leg makes my whole knee hurt. It seems to mainly focus at the back of my knee and under the knee cap. It also gets stiff and sore if I sit in one position for too long. No swelling or anything to see, just a general feeling of it being not right. No grinding or popping, though. I'm going to have to go to the doc's aren't I?