What kind of vomiting is it? The yellow bile vomit or is it the food too?
From personal experience... Lucy used to be on a grain free chicken formula (orijen) and would vomit yellow bile constantly. I'm talking almost every day - morning and night. Switched her off the chicken formula to a lamb formula with grains (innova red) and it completely stopped. The company stopped making the lamb formula, so i switched her over to a duck with grain formula (fromm duck). Vomiting yellow bile almost immediately started again. Switched her off to a grain free lamb formula (acana lamb and apple) and hasn't vomited once since she's been on this one. Lesson learned - no more poultry.