Every year, about this time, our Jack Russell gets something between her middle two toes on either of her front paws. It doesn't bleed, but swells up a little, and occasionally she holds it out for sympathy. She licks it more than somewhat too.
We were told by the vet that it was possibly new grass either causing a burn or a cut, but has anyone else seen this? It goes after about a week, and is then forgotten!