Oh my gosh. That made my heart stop when I read the first half of your post. I'm so glad that it wasn't worse. He may have checked out okay, but that doesn't mean he doesn't have a headache and some stress.
Since there's nothing medically you can do, I would simply forget the housework and errands today and just lay on the couch or floor with him. He wants to be with you and he's probably getting tired of following you around.
So nice of the driver!
Not so much with the other dog owner.
