We never had problems with our Boxer and our BullMastiff/APBT mix but our GSD was a itchy nightmare for years! The first years was the worst BLK/GSD so grey skin. His skin turned bright red and he was losing fur like crazy!
Never got as bad as the first year but it was annual vet visits and Fish Oil and Benedryl for years! I started using Coconut Oil some months ago. Huge changes very very minimal scratching every now and then, zero fur loss and no more Benadryl.
The fish oil from the vet never seem to make any difference that I could see and I did not like him getting the annual shots,
Don't know if it will work for your doggie but Coconut Oil is certainly not going to hurt, going forward.
Ironhide Kennels: Spice of Life: Coconut Oil