My son has a rug burn on his arm from a couple of weeks ago. It seems to be getting bigger and looks raw in the middle and is darker around the edges. It is round. He was also accidently stabbed with a pen near his knee and that is dark red and about the size of a dime. He says there is also a whitehead type spot near it. He says he has two additional red spots on his bottom. Someone suggested ringworm but I looked at pictures online and it doesn't look like that is it to me. What do you think?