I fell on my knee and it feels like something is popping.?

8 days ago I was running on my carpet, tripped, and landed on my knee. It really hurt but it felt like any other fall. Later I went to a kickboxing cl. When I got home my knee was swollen and hurt really bad. I iced it for like 5 days straight, elevated it, and took ibuprofen. Now, 8 days later, it's really bruised and I have a big scab. I can't run, jump, or walk a lot. When I touch my knee cap it feels strange and there's like popping stuff. It also does it when I bend my knee and I can feel it on the inside. I don't know what's wrong with it, but I'm genuinely scared.