Check your local library. If they don't have it you may be able to find it at a health food store. Changing diet to a hypo-allergenic kibble such as Nature's Recipe Lamb, Rice and Barley. Nature's Recipe is just one of them. When you change food, do it gradually by incorporating the new food with the old over a week or two.
Abrupt changes can cause upset tummies and diarrhea.
Give only the hypo-allergenic diet. Have a thyroid test done. Make sure that T3, T4 and TSH are tested. Keeping him flea free. I can't emphasize enough how important it is to keep your allergic dog's environment free of fleas.