About 3 days ago I hit the left side of my left shin on the corner of a bench. It hurt pretty bad if I do say so myself but when I woke up the next morning it was sore as all get out and the bruise was light purple and had a knot underneath it. Well as the days have gone by it turned dark purple, and now it's turning yellowish but the knot is still there. It's not near as sore as it was. It's still a little tender to the touch but not near as bad. I'm really worried about the knot. Is it something serious or just something that's gonna take a little more time to go away because I hit it so hard? Thanks for taking time out to read this, I really appreciate it.