Why It Causes Stabbing Pain In Knee When I Lift Anything?

i am 16 and was lifting weights with my local football team. i was doing deadlift for my max about a month ago and about halfway through the lift my lower back made a crack that i heard but mostly felt. i couldnt finish the lift and dropped the weight. now when i try to lift with anything that requires my legs it feels like someone is stabbing me in the spine. it seems i can do less all the time i cant even touch my knees without this horrible pain.
please help