Crystal,
Is it possible he got a tick bite or some other insect bite there? The hairy scalp is a common place for them to attach and usually there's no pain, other than a bit of itching for some. Ticks do release some enzyme or something that keeps the blood from clotting easily at the site so that could explain the deep color of the bruise.
There's a homeopathic remedy you could get at most health food stores that is very good for both deep bruising, especially when occurring on a bony surface with little to no muscle over it (also great for a classic "shiner"), as well as the number one remedy for any kind of puncture wound, which an insect bite is considered to be. Ledum palustre 30x or 30C potency would be good. It can help prevent any infection as well, especially if followed by Hypericum the next day. These are both perfectly safe to use and won't interact with any other medications.
Ifyou had seen him get a hard knock on his head or there was a really big lump or hematoma, Arnica montana 30X or 30C, a few doses, can help stop the bleeding quickly and reduce the swelling rapidly as well as reabsorb the blood in the hematoma. I give any of my kids a dose of Arnica if they hit their head. When my daughter who had ITP hit her head just a few days after diagnosis at 5k, she got a dinner plate-sized hematoma under her hair, while she was spending the night at a friend's house. (so, I didn't see it for at least 12 hours or more. ). Of course, panicked a bit as by then she was in some pain, slurring her words and disoriented. I gave her Arnica on the way to the ER and right before we went in. The CT scan, which took several hours of wait time, revealed that there had beenbleeding but now it had stopped. She was still in pain, though and they had nothing to offer besides Tylenol which did nothing. One more dose of the Arnica stopped the pain within 5 minutes. They had said that it would take several weeks for herbody to absorb the hematoma. With Arnica, it was all gone in less than 2 days. Good stuff to have on hand, especially with active kids, ITP or not.
April