Did I Shift My Kneecap When I Heard A Pop Sound In My Knee When Bending My Leg And Now It S Swollen And Tender?

Hi on Friday afternoon I pickup my left leg and bend it for see something under my foot and my knee made a pop sound ever since my that my knee Is swelling an di can t make my leg straight. It s tender and uncomfortable. What did I do? Did my knee cap shifted?