And that's the thing. While there is nothing visible on his skin that can cause irritation there can still be irritation without any visible cause. If the GABA doesn't work to any degree then we can safely assume this is purely behavioural.GABA is medication called gabapenton that is used for assorted conditions in humans and animals. Frequently used for nerve type pain.
I do find the vet's approach a little strange this time, but I do trust him.