I changed Bea over to Raw a year ago for the same issue, I gradually cut out all her treats as that where the type you can buy in Tesco.
Her outbreaks are almost nil, she currently has a ear infection that I believe was brought on my me feeding her cheese, she had systitus and I was using cheese to hide her tablet in!
The treats she now has are mainly fish skin based or dried meat, unfortunately it involves a lot of reading of ingredient.
I have her feet cut short the same as inside her ears and I don't over clean her ears, some vets wanted me to clean them twice a week!
I leave the Malaseb shampoo on her feet for as long as she will let me, for her that's about 4 mins
Hope the itching soon stops.
Sharon.