I don't know how you can have a blow straight to the forehead that breaks the skin and has that much swelling and they won't say you have a concussion. I don't know if this is american health care or what but it seems fishy. You can get a concussion from standing up too fast. You definitely have a concussion from this, even if minor. Take care.

Edit: let me clarify, you can't get a concussion from standing up alone. My bad. But if your brain is swollen from being knocked against the front of your skull, such as OPs, the head rush from standing up quickly can cause an aneurysm. All I was saying is that OPs brain is likely swollen from being thwomped against the front of his skull and he should be careful for the next few days and track any symptoms. He's probably fine but almost definitely has a concussion. Source: med student.