You will need to obtain a drug called "Mitaban" either from your vet or an on line supply company. Mange requires two treatments, read and follow the directions carefully - the animal must be completely coated int the medicine. Mitaban is also fairly harsh and will act like bleach on your clothes
Sacoptic mange, caused by skin mites, needs veterinary attention, usually for two
doses of a medication called Ivermectin, two weeks apart, to kill them. Steroids
may also be prescribed to stop itching.
You should wash him with a special shampoo for skin care. Also you can take some environmental sprays or some other medicine. I advice you take "Dermisil" dog vitamins. Also it could be vise to go to a vet and to take some antibiotics for a longer treatment.
Not medical advice: Mange is common in many domestic animals. Consider a topical cream. Try using a product called "elimite" it contains(Permethrin) 5% cream is a topical scabicidal agent