
Evening Primrose oil is a natural anti - histamine too.
I'd try and avoid dry food if possible and it could be a storage mite allergy, if its only on his face. If he is on dry food, I'd wipe his face after he's eaten and thoroughly wash the bowl before his next meal.
Only way to tell for sure what he may be allergic is to have a York test. These are not cheap but they should be able to narrow it down, as to whether its and indoor out outdoor allergy.
I changed my washing powder, not even thinking about it and 3 of my dogs were sensitive to it. It made members of my family itch too so I went back to the original stuff and nobody has complained since
Justine, Remi, Dixie, Saffie, Bronte, Marnie, Lottie and Molly