He's a year and a few months. He's a teacup chihuahua
It's likely what is called a "Reverse Sneeze"
Video example: http://www.youtube.com/watch?v=1UyBrb0Hhpk
Take him to the vet to make sure it's nothing to be worried about. Here is more information on this condition: http://www.veterinarypartner.com/Content.plx?A=2335