Hit on the outside of lower leg, has turned into mildly swollen reddish tender area causing occasional itching, warm lump. What could it be?

I hit the outside of my lower leg on a metal bar (on the side of a landscape trailer) 3 months ago. The area stayed bruised for awhile and has now turned into a slightly swollen tender reddish area about 2 inches in diameter. Sometimes the area itches (which I related to healing ). In the last few days, I have noticed a lump under the skin in the same area. The area also feels slightly warmer than the rest of my leg. I have noticed that as I get older, I tend to bruise easily and they do not seem to heal. Any ideas as to what this could be?