Taking your dog to the vet to have an exam would be the best option. However, if you would like to try something on your own first than do the following:
Since it sounds as if it could still be fleas: Please use a monthly topically flea and tick product or an oral anti-flea product such as Comfortis. Don't stop! Please use it indefinitely. Clean your house again with Flea Busters (available at a variety of online sites such as Amazon.com) which is safer than Sevin.
If after two months your dog's hair doesn't come back in you must take him to the vet for evaluation and diagnostics. Hair loss can also be due to skin infections, mites, allergies, endocrine disorders and more.
Sevin Dust is TOXIC to dogs......Go with a product that your Vet prescribes....
thank you. i looked at dog this morning. he does have fleas. am taking immediate action