Hi and welcome!
If you'd like to go see someone who specializes in vascular birthmarks, let us know where you are located and we'll see if we can get the name of a physician that knows about hemangiomas.
I *think* I saw your name in the database, so I suspect you've already asked one of the experts, but if not, here's the link: http://birthmark.org/experts.php
Other parents will be in soon, but you'll get more feedback if you post a photo. If you find that a pic is too large or won't post for some reason, mail it to firstname.lastname@example.org
as an attachment and I'll take care of that for you.
In the meantime, try not to panic. It will all be OK. Go smell his head. I love that new-baby-head smell. They should bottle that!