I HAVE A MALE STAFFIE,7 YERAS OLD AND HAVE LATELY PROBLEMS WITH HIS SKIN. IT STARTED OFF WITH SCRATCHING HIMSELF ALL OVER AND THEN THE HAIRLOSS CAME.HIS FACE, HIS BACK AND MOST OF HIS LEGS HAD NO HAIR. I TOOK HIM TO THE VET MANY TIMES, EVEN TO DIFFERENT ONCE. ALL DID A SCRAPE TO SEE FOR MITES BIT THERE WAS NON.FINALY THE VET PUT HIM ONTO ALERGECS, MICROCIDAL AND PREDNISONE. OCE A DAY I HAT TO SPUNCH HIM OF WITH IMAVERAL MIXED WITH WATER.IT STARTED HELPING AND THE HAIR GREW BACK.WE STOPPED THE MEDICATION AND SOON AFTER THAT THE DOG STARTED GETTING LIKE LUMBS ALLM OVER HIS BODY AND MARKES ASIF SOMETHING IS WALKING OVER HIM AND EATING THE FURR LIKE LITTLE PATHS.AS SOON AS WE PUT HIM BACK ON THE MEDICATION THINGS START LOOKING BETTER BUT IT DOES NOT COME TO AN END.THIS IS NOW GOING ON FOR MORE THEN 6 MONTHS. PLEASE, IS THERE ANY THING YOU COULD THINK OF. I AM LIVING IN CAPE TOWN, SOUTH AFRICA AND THE VET TOLD ME THAT THERE IS A LOT OF POLYN IN THE WIND AS MOST WILDLIFE FLOWERS ARE BLOOMING NOW. CAN IT BE AND WHAT CAN I DO.
KIND REGARDS. RUDI

Food allergies are a possibility?
If there has been any recent changes in the diet?
It could be a seasonal allergy? Might be worth having your vet do allergy tests

skin scrapes are inconclusive so blood tests should be done to test for parasites/food intolerance/inside and outside allergens.  Costly but the only way to find out what is causing it. Hope you get it sorted soon.

Definitely check for food allergies or environmental allergies. It might also be worth checking thyroid as that too can sometimes contribute to skin problems.

Vera