Those spots on Dingleberry could be several things including allergies, skin mites, flea bites, ringworm (which humans can get) or a bacterial infection. You can try adding in an omega 3 fatty acid supplement for dogs, this can help improve the skin health. You may also try changing his diet to something like Royal Canin or Nutro as they are aimed at skin health. You can wash the lesions with soap once a day and rinse well (don't wash his whole body, just those spots). Protect the areas from licking or scratching. If they don't start looking better within about a week or if they get worse, have him examined by the veterinarian who may prescribe medications. Best of luck and please feel free to post any additional questions.