Whats wrong with my knee? ):?!

I hurt my knee playing basketball
After a jump i landed on the floor
I felt something in my knee slip out
As my leg twisted and gave out
I fell down and sat their for a while
Someone helped me up and i went to put
My weight on my left leg to walk
My knee just did the same thing it did when i landed from the jump and i fell
I cant walk or put even a slight pressure on my leg
Whenever i accidently put weight on my left leg, it is the worst painn i have ever had
My leg is swollen under my knee cap
And on the side its black and blue
My knee hurts usually at night and in the morning for some reason which is weird
It isnt like searing pain, just like slight pain which feels like a muscle spasm idk how to explain
I cant seem to straight leg out when standing up and when i can my knee is sticking out
Whenever i try to lift my leg i have to use my hand cause it wont on its own
And whenever im sitting and i try to bend my leg it hurts and it feels like the top of my thigh is puting pressure on it not to bend and the side of my leg hurts
Im really scaredd, idk whats wrong with it