Hello, I have a 3 year old son, and about 5 months ago he was hit in the forehead by a metal gate that swung open very fast. He got a bruise/bump on his head very quickly, but he jumped up and wanted to keep playing, so we didn t think it was that serious... however, now 5 months later he has what appears to be a permanent bump on his forehead in the same spot (no discoloring). Is this serious? should it be checked by a doctor?