One cause of patches of hair loss in dogs is a fungal infection. Ringworm is an extremely contagious condition. When a dog has ringworm, fur falls out in small circular patches. The bald skin that is revealed can be marked by red lesions that form a circle. Dermatophytosis is another fungal infection that causes patchy fur loss. These infections can be easily treated by a veterinarian. Once the fungal infection has cleared up, your dog's hair will grow back normally.
Mites can cause a dog to lose hair. These tiny insects live in your dog's hair follicles. If your dog has hair loss in patches that are especially pronounced around the head, neck or feet, then he might be infected with mange. Depending on what kind of mite is causing the mange, it could be passed on to humans. Demodicosis is caused by Demodex mites and also causes patches of hair loss. A veterinarian can determine which mite is causing the problem and prescribe a rinse or injections to eliminate them.
It could also be a flea allergy- has he been treated for fleas recently?
If your dog is losing fur in patches and is scratching more than usual, then allergies might be to blame. If you washed your dog's blanket with a new detergent and your dog is allergic to a chemical in the detergent, that can lead to skin irritation and itching. If it is bad enough, your dog can scratch its fur out and create bald patches. Removing the allergen will stop the allergic reaction and the hair loss should stop.
If you haven't already I would go and see the vet, as some of the things you have tried at home have not worked.