It sounds as though your dog is allergic, or at least sensitive, to the ingredients/food. Minor reactions can include vomiting, hives or other skin irritations. A more major reaction is when swelling of the face or body occurs.
Dogs suffer from allergies more often than people think, and can be allergic to fleas, dog food ingredients, seasonal stuff such as pollen, dust, or even grass or laundry detergent etc.
Most allergies result in skin problems, whereas sensitivities or intolerances result in tummy upsets. You can find out a lot about dog allergies and what kind of products to use to help relieve them at
http://www.the-puppy-dog-place.com/dog-allergi es.html