I did a sort of strenuous work out yesterday, and today my knee made a crackling noise when I bent down. A few minutes later, I was lying down and when I tried to get up, my knee made the crackling noise again and buckled underneath me. It hurt really bad. When I used to dance I got a meniscus tear in my opposite knee and had to wear a brace, but this knee hasn’t been damaged before. I’m 20 years old and female. I don’t work out regularly.