The vet is always the best option.
My dog (min pin mix) experienced some of the same symptoms, hair loss, itching, redness, and a foul odor. I later found out he had a grain allergy, I've switched him to a grain free dog food and also give him 1/4 cup of plain yogurt everyday. I would say that about a week later I started noticing a change. It's been over two months and he is completely back to normal, occasionally he starts to itch and I immediately put a little bit of olive oil on the spots. It seems strange but it works for me and my dog, every dog is different thought so first things first call the vet.
