sounds like he is allergic to something (maybe you) . LOL[],lets hope not.
you may have to take him to the vet. if it doesn't stop.

my new pup wants to scratch all the time.he doesn't have a single flea(not one).
we wash him regular,his skin is clean and soft.real fine hair.don't know???
I'm gonna try some head and sholders and see what happens.
He loves the water,he will try to eat the water out of the spiket or end of the hose.
I know all dogs scratch to some extent,????