I was playing soccer and a girl kicked the outside part of my left knee really hard and i can barely walk now. did i tear something?

Possibly: Soft tissue injury can be painful and debilitating...It is possible that you may have torn something....Pain and debilitation are part o nature's way of telling you that something is wrong....Best to stay off of it and see your family doc for an evaluation and possible imaging studies..Soon!

Possibly: You may have swelling within the joint from damage to any of the structures within. Keep the leg elevated for now & you can wrap it in a pressure wrap.A cold compress can help with the pain & decrease the swelling. You need to set up a visit with your pcp in the next day or two to sort this out.Expect the swelling & pain to increase some if you are up on your leg. Find some crutches to get around.