Agree with Han. He needs to be rechecked.
I feel you either need to take him back to your vet for further
testing and evaluation, possible head X-ray or ultra sound
or a second opinion form a diferent vet,it's NOT normal for
your puppy to be sleeping this much...
What did your vet say when you called them back to tell
them about his sleeping so much and for so long?
Your vet checked for possible head injury(?) what were you
told to watch for so far as a concussion and symptoms??
Please come back and let us know how this turns out as
your information could help others.
I hope your little guy gets better...
Jan