Zach,
 
This may be a dumb question, but have you given him a bath of late.
 
I once washed my dog and afterwards he did nothing but itch all over.
In desperation a couple of days later I took him to the vet.
 
He had dry skin, which the vet said was because he hadn't be rinsed
off fully after his bath and there was still soap on his coat.
 
Or you might want to look again at the dust problem - if there is a lot
of dust around still - then that could be causing his skin to dry out,
making him itchy.
 
Hope this helps.
Danielle Dixon & Ollie
[Posted in FML issue 4111]