Head injuries are deceptive. I’ve read about many related to toddlers. They fall and hit their head on something. They cry and then stop after some consoling. They go to sleep shortly afterwards and don’t wake up.
It’s scary. It’s one of those injuries that’s hard to detect. They appear fine.
I think the recommendation from doctors is to first check the injury, and then see if they’re playing around afterwards. If they appear lethargic and tired, then you better take them to the doctor and have the injury checked out immediately.
Senh: Good thing a parent recognized him or something would have happened to one or more of those kids.