Suggest Treatment For An Ankle Injury

On 4/2/11 a car door closed on my left ankle. I immediately iced it so it never turned blue/purple/yellow. The inside tissue continues to be hard and a little tender. Sometimes the area feels like a sunburn, and my foot swells a little. It is not painful when I walk. Do I need to be concerned about an infected hematoma or cellulitis? I have had both in the past (~7-10 years ago). What should I do about this? I am 68 years old, have asthma and mild osteoarthritis, 5'2" 175 lbs.