I was thinking yeast as well; my Willy is highly prone to this sort of thing. For him, I have to be sure to use grain free food and treats -- yeast feeds on carbohydrates, so the grains are out.

The large area above your finger (first photo) 'could' be a hot spot developing. If it is, you can apply Gold Bond powder up to 3 times a day to help it heal.

Let us know what the vet says!