What Causes A Worsening Painful Bruise On The Shin After A Three Wheeler Mishap?

I had a 3 wheeler mishap last weekend. Bruised my left shin. Its almost a week later, and the bruise (and pain) seem to be getting worse instead of better. One area just below the knee is particularly swollen and painful, and the redness and discoloration seem to be moving down my shin. Should I visit an emergency room, or give it more time?