What Causes Redness, Increased Pain And Warmth After Being Bumped?

I bumped my shin a week ago. swelling and bump was present for a few days. Bump has resided but the entire front of my shin and the sides of my shim are painful to touch. There seems to be some redness and warm to the touch. I found bruise way down below my ankle on the inside. Could it be bleeding and collecting below my ankle. Why would the pain seem to have expanded and feel warm?