question: So lately sometimes my knee will just ache/hurt or feels like there s an air bubble in it. Sometimes if I pop it the air bubble feeling goes away. It doesn t always hurt but sometimes it does. When I walk up and down stairs my knee will hurt. I m a klutz so I do trip/fall a lot. When ever I run or do much on my knee it hurts. Also it will pop and crack a lot. This happened a lot last year and then went away for awhile and it s came back. And when I sit down sometimes for awhile it ll start to hurt.