Hi Amanda G:
Environmental, food sensitivities or allergies, and an unbalanced diet can all contribute to the symptoms your dog is plagued with. I would also look for a Veterinary nutritionist to help formulate a balanced homemade diet. Most will do phone consultations with your regular Vet if you are unable to find one local. Most Veterinary schools provide nutritional consultation services too. Good luck!
Here is a site with info on homemade diets:
http://www.dogaware.com/articles/wdjhomemade1.html
http://www.dogaware.com/diet/bookreviews.html
