My golden has blood test & skin test before but still not cure. Change the medi shampoo together with Sensitivity Control diet helps a lot. Have you try Malaseb shampoo before ? Or you can seek Veterinarians to refer you a medi shampoo too. Try Dr. M. Bradley at Stanley Veterinary Centre, Dr. Tiint Naing of Soares Avenue Paws & Claws Clinic, both are very experience.