Need help over there. Bull terrier with serious skin issues.

Largo

My 7 year old, 22kg, male/neutered, white bull terrier had some minor skin problems over the course of his life, but every time we were able to treat them with my vet. Since November the problem seems to persist. Then we went to a specialist dermatologist vet. As you can see in the photos, he has all sorts of dermatic issues. Red areas between his toes that sometimes get swollen and wet, pyoderma, the inside of his ears gets red and super itchy and of course red blisters in various parts of his body. The initial test report from a sample taken directly from a wound was Staphylococcus pseudintermedius in small population. After giving the dog various antibiotics (Zinadol, Augmentin) that did not work, the doctor decided to treat the wounds topically, with amicacin and frequent baths with detol foam. That did the trick to kill the microbe. Latest test report showed no microbes in the wounds. The dog has also been negative on test for Leishmaniosis. After that, the specialist prescribed my dog with prednisolone for 10 days combined with antibiotics just in case. Most of his wounds dried, but after the 10 day period passed, he developed new wounds. Then the vet prescribed us with apoquel but after almost 70 pills it doesn't seem to work. Last, the dog is on a strict diet eating dry Aatu single protein Duck and some fruits(bananas, green apples, carrots, cucumbers). Also we are based in northern Greece.

https://imgur.com/h8zqg7n

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Blood Test and Test report (in Greek, can translate if needed)

https://imgur.com/dzY7cJZ

https://imgur.com/8GB2nh2

Djammy

WOW! This looks bad!
I am not sure if I can be of big help. Because, sadly, while Bull Terriers are prone to skin issues the causes can be manifold: food or environmental allergies, parasites and microorganisms, infection and more.
Something I suggest over and over for every dog with skin issues is boosting the immune system with appropriate supplements (vitamins&minerals). They do not heal but in the long run a strong immune system is like a well equipped army: Simply better prepared for the fight against ailments.

Is your dog itchy, scratching and biting itself a lot and therefore the bare patches? Or how does the hair go?
Was it tested for mites?
Has anyone ever taken a real close look at the nutrition and have you ever considered feeding a raw homemade diet? Sounds like you are already feeding a special food?
Did the tests reveal any definite allergies?