You would need to take him into the vet to get him on Baytril. They would prescribe it for him.
If his belly is dragging the ground, I would definitely get some fleece on the floors of his cage. It'll really help make him more comfortable, and will also keep him from getting any scratches from the bars. It will also help keep his belly out of his urine and poo, which would cause some problems even with healthy skin.
Just keep what you're doing. Keeping him and his cage as clean as you can, compressing, and flushing should all make him better.
If his belly is dragging the ground, I would definitely get some fleece on the floors of his cage. It'll really help make him more comfortable, and will also keep him from getting any scratches from the bars. It will also help keep his belly out of his urine and poo, which would cause some problems even with healthy skin.
Just keep what you're doing. Keeping him and his cage as clean as you can, compressing, and flushing should all make him better.