I had a knee injury 2 days ago. I fell straight down on my knees, both swelled immediately. My left knee and shin are injured more, the left knee cap on the outer side has sharp pain, there is a dull pain down my shin to my ankle .
could I have torn something? I had X-rays at the ER nothing is broken.

X-rays don't show soft tissue damage... only bone damage.

I'd go to a sports medicine specialist... we can't guess how minor or serious it might be via the internet..