My 3.5 year old english mastiff, Titan, appears to have developed sores between his toes. The sores look like two swollen fluid-filled bumps in the webbing of his toes. Last year we had a problem with cheatgrass, but he hasn't been exposed to any this season. I would really like to hold off from our bi-monthly pet visit if possible. We have some Sulpha antibiotics that are here, should I start him on a round? He isn't very responsive to us trying to mess with it and I'm afraid my vet will want to put him under to take samples that may be unnecessary and expensive! What do you think?