I think that often if there is an injury caused by a fall from height, it is to the jaw. Cats have the ability to absorb a considerable shock, but when the fall is too high it is the head that strikes the ground.
As your cat is eating normally, it looks like he got away with it.
If he doesn't seem himself, it might just be that he isn't happy having been stuck outside overnight in the cold. Possibly a little bruised, but he'll get over that. The last thing he wants is to be poked and prodded by a strange man in a room that smells of dogs.
I would just make a fuss of him, and let him have a good sleep. Only worry if he is still out of sorts after a few days.