While walking into the school (teaching in) I slipped on black ice on cream colored concrete and went down on my knee with a twisting motion. I did not have pain at first but it swelled up a bit and then for the rest of that week I had a bit of trouble with it including trying to ice it which caused the pain to become more intense, straitening the knee and walking. That was back in say march and were now in may just wondering what I might have done to it.