Is he still alive? Are the sores any worse? It looks suspiciously like red leg. This condition is usually fatal, I'm sorry ;-; It's not easy to lose a frog buddy. Have you purchased from this breeder before? Red leg is caused by overcrowding and unclean conditions. I would quarantine him immediately. Keep his quarantine setup simple: paper towels substrate, water dish, a couple of hides. Keep misting him as usual. Red leg can spread in a tank like nobody's business! My advice is: Keep him clean, keep him fed, keep him separate from any other pets, do the best you can for him, and say goodbye in case he doesn't make it.