Well, it certainly sounds like atopic dermatitis (environmental allergies) or some other skin condition. It sounds like the dog is in extreme discomfort and at risk for bacterial skin infection.
Anything anyone tells you on these forums is just speculation and opinion (myself included)
If your veterinarian has not been helpful I would ask for a referral to a veterinary dermatologist for testing to come up with an accurate diagnosis and treatment options.
There is no miracle cure or magical supplement or food that will fix this.
In fact the dog may have to go on steroids and antibiotics again to temporarily stop the suffering.
Consult your vet, asap.
