If this were my bird, I would be painting his leg with iodine. Just a thin covering of it. Colored or non colored, doesn't matter. Iodine is readily pulled into the skin and is a good topical treatment to use because of this. Paint it and leave it, don't cover it. I know that the lower percentage of the iodine we can get now isn't supposed to burn the skin, but there's no reason to chance it. As the iodine is absorbed, it will kill any infection it comes in contact with. If you can do it, a good soak in warm water would help. Not overly warm, just enough to help make the skin/scales softer and more able to let the iodine into the underlying skin. The internal antibiotic isn't going to hurt even if this doesn't turn out to be an infection. My choice would have been one of the tetracyclines as they are better able to get out to the extremities faster.