Knelt down yesterday to change a nappy on the floor and thought I'd knelt on something, there was a horrendous shooting pain through my kneecap. Got up, but nothing there. Did the same again later that day. Kneecap looks swollen but no bruise, although when I touch it it does feel bruised. My family has a history of knee trouble, so what have I done? Is it cartilage? Will it get better or do I need some treatment? Am avoiding kneeling at the mo! 