These little guys can get hurt so easily...but 
they don't know that.  I own a 2.5lb fella myself so I can sympathize.  I can't say that I've ever had a dog that had a concussion, at least not that I can remember.  A suggestion though:  Keep your dog off the bed.  (Or anything high where falling would present a risk, for that matter.)  Or get some stairs or something where he can easily get up and down. 
I hope he has a speedy recovery.
 
  
Welcome to YT!