Add some brewer's yeast to the dog's food. You can buy it in powder form at a health food store and add it to their food. They have it in pill form at pet stores and walmart. Avoid the kind with Garlic in it. It can cause gas.
It works on my dogs! My old Eskimo Spitz eats it like a treat! Although my Scooby may be allergic to yeast. It does take a few days to get into their systems. It is also supposed to help with fleas but haven't seen it do much for that. However, their coat will improve and help with shedding issues.
Also try increasing combing/brushing. This should help spread natural body oils throughout the coat and skin. My short hair dog LOVES to be brushed. The wire brushes work well and it helps with "Scratching". Which I am sure the dermatitis is doing.
Gives some benadryl if the itching gets too bad. My 35 lb dog has taken a full pill and been okay. However, I like to break the capsule and get the powder in their mouth or on food.
My neighbor has 2 fawn colored Dobies! They are outside but have shelter. They are soo sweet and cute! One of them is named Benji just like mine! Adds confusion when I call .
I understand why you keep the doggy outside. If you make that choice then make sure you keep making the effort of clean water and bedding. Not every dog can live inside with you. I wish I had kept my adopted Boarder Collie outside. She's too big. Also she has peed on the carpet and eaten my furniture! She was a lost dog and I believe lived on a farm. It has taken ALOT of time and patience to get her to adapt to living indoors. It is still a work in progress!