What Does Bruised, Red, Painful Shin After Being Hit Suggest?

age 31, height 5'11 Playing football 9 days ago and I took what at the time felt like an innocous knock on my shin , later in the session my leg started to swell, the following day my leg was bruised from my foot to half way up my calf muscle and still is now. Further up my shin is now starting to come through as a red surface colour and is very painful to touch or when leg is moved (this pain is awy from the impact location) any ideas?