Dislocated kneecap or torn ligament or what?

Last summer I was doing spiking drills and I had gone up to spike. When I landed a felt a sharp pain in my left knee& I felt something go to the side which made me fall.

After, I couldn't put any pressure on my left leg because my knee hurt (specifically the the outside& back). I went to the doctor the next day& they took an x-ray& said nothing was wrong with any of my bones. So they just gave me a brace and I was on my way. I kept the brace on for 2 weeks& when i took it off and tried to walk but there was this tightness in my knee so much I couldn't even bend it. When I would touch my knee I felt this kinda of sqiushy Feeling around the bottom left of my knee cap.

Ever since it feels unstable.Sometimes even doin the simplest things such as getting up from a stool or even walking also running full speed and jumping my knee would give out/collapse& something dislocate.After, sometimes comes a very uncomfortable pain.

Can anyone tell me whats wrong& what can I do
It sounds like you dislocated your knee. I've done the same--the doctor ran x-rays and said it was fine. It probably just popped back in place and damaged a lot of the cartilage around your knee. Be very careful on it--if you do have cartilage or ligament damage (like I did) it will slip right back out of place again. Except you may not feel it because you could have nerve damage. I had to go to a specialist, wear a brace, use crutches for months, physical rehabilitation, etc. I hope you don't have to go through that. Definately go see a specialist. Your every day Physician may not identify it until it's too late.