Min Pin very "tired" and timid after concussion

This weekend I had family visiting from out of state. I am the proud owner of two very playful lovable min pins. Oliver is the youngest (6 months) of the two pups. My sister-in-law was picking Oliver up in the driveway and managed to drop him. I did not see the fall but I did see my puppy motionless in the driveway seconds after the fall. She claims the fall was only from about knee high but I question the truth in that statement. I panicked and picked him up running him back to the house. I laid him across the floor and examined him to the best of my ability. Oliver was completely unconcious and limp, his face appeared to be tense as one side of his mouth was open and his tongue was out. I thought for sure little Oliver was dead. I put my hand on his chest and felt his little heart beating. Instantly picked him up and drove him to the nearby emergency animal hospital. About 20 minutes after leaving the house Oliver began moving his head but nothing else. The animal hospital kept him overnight informing me he had a concussion but did not appear to have any skull fractures or broken bones. I was able to pick Oliver up the next day. Oliver is at home now but he appears to be very lethargic. He will NOT go anywhere near another person. He will follow me everywhere I go and will NOT let anyone else touch him. I am very worried of possible permanant damage. The animal hospital told me to make sure he takes it very easy for the next three days. It's day two and I am still worried. He is eating normally and drinking water.....then he sleeps. I am sure he did not sleep well while at the animal hospital but he really seems to be sleeping ALOT. Oliver was always the playful sweet type of puppy that would cuddle with anyone who started petting him. He will not let anyone even my wife touch him. He actually bit my father-in-law when he tried to pet him. This is VERY unlike Oliver I am sure he is still recovering from his experience but I am worried that something else may be wrong. He does not have any damaged teeth, bruising or bumps. The animal hospital checked his ears and did not notice any bleeding....am I over reacting? I am very worried about little Oliver.

[have 2 kids]

I think I would contact your regular vet and get his/her opinion.  It can take some time to recover and maybe the tiredness is normal  however it seems like his personality has changed.  Good luck.

[MinPinner]

I have checked up with our regular vet and he told me to wait a few more days. He said if his behavior does not return to normal to bring him in to be re-examined. I just went to check on him a few minutes ago and he was very excited to see me. Tail wagging and hopping around...seems that his normal behavior may be returning. I apprectiate your post. Thank you

[have 2 kids]

That's good- I hope he starts being comfortable around others now.