I need help

Hey guys, my female dobie (7months) has had some hard skin problems since birth, and the vet is having a tough time. This seems to be an allergic reaction but i have tried every type of food (hydrolyzed protein included) and nothing seems to work. All types of shampoo and antibiotics have also been tried. The only thing that seems to work is an anti-inflimatory but its a temporary fix. Has anyone had this type of problem?