Vic there are a lot of suggestions, Im sure, we always used spray little clorox on spot. If you want sure cure go to vet, buy a bottle of Gen One cost very low. about two applications spots will start to go away. Buddy
The vet told us it was something like staph. Ours get it from running in the pen. Our vet gives us bactrim to give ours 2 times a day until spots are gone.
Give 5cc sodium iodide 3 days in a row. If it doesn't dry it up continue for a couple more days. You can also rub their legs down with bleach. Mine had same thing. Took it to vet and they said it is a fungus kind of like staph. If you want to cure it get some sodium iodide.