First and foremost, has the infectious agent been cultured...?!! Or at the very least, did the Vet take a skin smear and look at that under the scope and confirm it was bacterial in nature...?
Are the sores around mouth/eyes due to him itching there or ?
It would really help to see a picture of the sores, as well as belly.
I can't fathom why, with recurrent infections, the Vet is using clavamox
! Your dog should be on Simiplicef x 28 days if this is bacterial (ie, pyoderma).
Whenever there are recurrent skin infections like this that cannot be tied to allergies, thyroid should be checked AND Cushings absolutely should be considered. In addition, Diabetes should've been discussed for sure bc of the blindness -- is he diagnosed w/ juvenile cataracts then or.....?