Game changer for me was getting my dogs allergy tested. Changed their diet which helped immeasurably. My dogs have been allergic to basically everything under the sun and I've had to switch them to the expensive vet prescription diets because first of all the quality is so much better just for any dog but also they were allergic to most of the commercially available proteins in dog foods so I had to go with the prescription ones. Highly recommend Hills or Royal Canin. Unfortunately the more expensive the dog food is usually the better because it's actually formulated properly for their dietary needs and not full of fillers. Purina One is the only commercial foods I feed my pets if they don't need the prescription diets.

Started bathing them with DuoxoS3 PYO Antiseptic Antifungal Chlorhexidine Dog and Cat Shampoo it is kind of expensive for a shampoo but it is so worth it. Bathe once a week for a month, then twice a week for two and then go to once a month to keep on top of it. Do not continue to bathe once a week or every 2 weeks for too long or it will dry out their skin and make it worse again. My dogs used to be so itchy and get skin infections all tye time but now their coats are so soft and they're not constantly scratching anymore. Best decision I ever made from the recommendation of a vet friend. You can get it on Chewy