From what you have told me, it appears that your dog is suffering from some type of allergic reaction. This could be due to anything such as dust, pollen, fleas. The constant scratching can cause a secondary pyoderma or skin infection or what you are seeing as Hot Spots. The first thing to do is to give your dog Benadryl that can be purchased over the counter at any pharmacy. Give your dog Benadryl at 1 mg per pound of weight given twice a day for 1 week. If there is a secondary pyoderma, apply Betadine to these areas after clipping away the hair. This can also be purchased at any pharmacy. If there is no response in a week’s time, you will have to have your vet examine your dog to see if we have missed something such as parasites or other infections.