Stinky breath!

Reg has the most awful breath, he's on Naturediet and his teeth were checked by the vet prior to leaving the rescue and where ticked 1 on his health check (1 = no problems)
So maybe it's his gut that's the trouble.
Any tips?

Oh, also he has a very dry rough nose, I put this down to being snotty when he had kennel cough but it's not improving, do I leave it alone or can I put something on it to help soften it?