I Misstep-ed From A Bus Recently . I Had Pain

I misstep-ed from a bus recently . I had pain at the back of my R knee . During the first week , it was very painful to walk . The pain ameliorated with Tylenol and Ibuprofen. No redness or swelling was seen, just a soft bump I can feel in the back of my knee. Now I can walk almost normally without pain.But if I run or walk fast , the pain comes back.