On a whim one day I bought a bar of BASIS SOAP, original, to try on my dogs feet. I lathered it up, put it on their wet feet, let it sit there a minute or so, then gently rubbed it around & rinsed completely. Sometimes I have to use a little piece of a washcloth to help get the brown stuff off their feet because it's sticky. It's from the allergens in the grass, etc. Cost $1.25 at Walgreens/Wallmart.It's usually on the top or bottom shelf in the people section of bar soaps.. By the next morning there was a HUGE improvement. If it's your Shepard in the avatar that has the problem you could probably put 1/2 a bar of the soap in water & let it "melt"& make a "shampoo" out of it so you could work it down to the skin easier. So I told my daughter & she took 1/2 a bar home & tried it on her English Pointer who has white skin & fur & has a terrible time with entire stomach, under "arms" & feet. They were very red, itchy, & had little tiny pin dot sores. It worked GREAT!! Now we both use it on the dogs about once or twice a month. It works for allergy problems by washing away the allegens but not drying out the skin because it has alot of fatty acids in it. On my dogs (Weimeraners) I can see the build-up of allergens on the skin. It makes a brownish kind of sticky stuff that builds up & I can really see it between the toes & on the back side behind the pads. And my daughter says her English Pointer will get "stinky". She says "stinky pits". Her dogs skin gets very red.
As far as the food, look for one with out any grains. Grains are the #1 cause of food allergies. We like TASTE OF THE WILD. It comes in several "flavors".
ALSO, there is a prescription med that comes in a tube called ENTERDERM, it helps( altho I mainly use it only on the feet for interdigital(between the toes) cysts & the prevention of the cysts-they are extremely painful if they form).. The tube is small $20.00 here.It works good for a variety of problems, but I don't think you could get it thru alot of fur, but would work well on places where the skin is easier to get to.It is a combo of 4 meds & covers a variety of problems from infections to bacteria, & other things..
Please try the BASIS SOAP! We were just amazed that something so cheap & simple could make such a huge improvement! We told our vet about it & he is now recommending it to his "patients".