I bet they are real dry and are itching or maybe flies are irritating them I'd put Vasiline on em he ain't gonna wanna lick them with it on em and if it's flies the Vasiline should keep them off.
The last thing I'd do is put pepper sauce on em that would irritate them more and he'd more than likely eat them off.
x2....poor guy, could be the treated wood. Some dogs have more sensitive skin than others.