DD did this onto a concrete floor and I got her checked out at a minor injuries unit as she said her neck hurt and she was a little pale afterwards. Doctor said the paleness was just shock and that her neck was just a little pulled.
If you are at all concerned try calling your GP's out of hours for reassurance.
This happens to children all the time with no ill effects !
My dd1 was constantly doing similar things and was fine. Just constantly bruised.
If he appeared fine, as you say, he probably is. With dd I would rouse her a bit when we went to bed and then again in the night at some point just to check they were ok (you don't need to wake him fully, just so you can tell he's asleep, not unconscious).
Is there an out-of-hours doctor's number on your gp's answerphone? You could call them. That's what we do when we need advice out of normal hours. They're very good and if they're at all concerned they'll make an appointment.
But, in my experience they will just ask you all the questions that you've already answered - did he cry straight away? Has he vomited? Does he seem happy and alert when awake?
You could just go and move his covers / kiss him and see if he rouses (only rouse him, don't wake him.
It's terrifying when they fall and bang their heads isn't it?
Ring your Dr and see if there's a number you can call so you can speak to a medical professional for reassurance.
It is horrible but in 24 hours you will either have seen him get worse (very unlikely) and got him some help, or he'll be fine - just keep an eye on him for the usual signs (vomiting, not being rousable, disorientation, check both pupils look roughly the same). I hope the time passes quickly for you.