What Causes Pain In Knee And Difficulty Walking Post Injury?

Hey there Doc! I hit my knee really, really hard on the end of the table.... It was a sharp, funny, hurtful feeling pain. I sat down immediately. Although the intensity of the pain level went down, (not by much) it still hurts when I start to walk, but also it starts feeling funny with slighter pain when I keep it steal for a minute or two. I can feel it sliding so I tried to stretch it because the feeling is aggravating. When I did that I felt it kind of popped when I loosened it. It kind of pops every time I try to stretch it. There s a small dent the size of the corner of the table in my knee that I can feel. Overall, my knee just feels really irritated and I don t wanna walk on it. Can it be serious Doc?