My Child Was Kicked In The Shin One Week Ago.

My child was kicked in the shin one week ago. It became very large. Went to ER to make sure it wasn't broken. They said it was a hematoma and to watch it. Now, a week later, it is yellow, I know is normal, but it still has a large knot that seems harder then before, my main concern is that the area of the swollen knot is warm to the touch.