Sorry, but by now you realize it was not a good idea to put those puppies on the bed. The pup can have a serious injury to it's head, neck or spine. I suggest you get it to the Vet fir an exam. There is no way to reassure you.
*Is he old enough to sustain a small knock to his head without it causing any damage besides a slight concussion?
Probably NOT! You need to get him to your Vet ASAP...Good luck & let us know how he is.....Karla