Anyone ever deal with a cat that had mange or some sort of skin infection/allergy?

Mr. Sofite's skin on his head and neck is all scabbed up and he keeps scratching himself and crying when he does it, it obviously itches and hurts him. Trying to figure out if there's something I can do to help him outside of the vet, since I'm not sure if my dad will pay for him to get seen or not.