Sulfadiazine is better than neosporin which can cause scale softening in some cases. I would switch to paper and keep it dry and clean until it clears up. Remember people on line can only guess. You need to decide what it is based on the conditions and evidence presented on the animal. The rest of us can only observe and judged based on images. Keep a close eye on it and if it gets worse a trip to the vet is best. A vet trip should be something you have already considered anyway.
best of luck.