Hi i have a 4 year old son, he has gotten a bruise on his forearm that is about 4 inches in diameter. The bruise kind of looks like it is just a ring and in the middle it is his regular skin color with some red discoloration inside of it. The entire center of the bruise is bulged up. He complains of it hurting, and even though he is a very active little boy, he hasn't been using his arm as much as he usually does. It is on his right arm.