He could be going through a fear period? Have you experienced this yet. Things that the puppy had no issues with can suddenly scared the bejesus out of them. May want to check out these links for some information.
http://www.dogclub.co.uk/advice/puppygrowth.php
http://www.geocities.com/mistybluecollies/criticalperiods.html
http://www.vonfalconer.com/puppy.html
Though some of the above periods are supposed to be relatively fixed in the time period, others may varied from the schedules shown.
Hopefully others will come along and offer some insight as well.
Good luck.
http://www.dogclub.co.uk/advice/puppygrowth.php
http://www.geocities.com/mistybluecollies/criticalperiods.html
http://www.vonfalconer.com/puppy.html
Though some of the above periods are supposed to be relatively fixed in the time period, others may varied from the schedules shown.
Hopefully others will come along and offer some insight as well.
Good luck.