Is my knee going to be ok??? :(?

Ok so about two weeks ago I hit my kneww on the corner of my sons' crib. It hurts now only if something hits it, Im not limping or anything. But today I went to touch it and I felt this crackling inside it. Like a bunch of air bubbles popping .And when I flex the my leg, I feel the crackling too. Its not the bone though. What should i do. Should I just wait it out and hope it heals or go to the doctor(hate going). Could it be permananent? And what could the crackling be?