Throwing up

Question
i have a 4 year old toy poodle and i recently changed her food because i was currently buying her small dog food ultra b/c at petsmart they said that is the top of the line, but lilly (my toy poodle) didn't seem to like it very much and only seemed to eat it because she was hungry, i changed her food to the natural choice (i believe it's called) which the people at petsmart said that it was below ultra brand, now that i bought her the new food, i usually just leave out a full bowl of her food so she just eats it whenever she's hungry now she throws up every other day, one night she threw up 3x and i just don't know what to do, she seems to like the flavor but is it upsetting her stomach? should i stop feeding her that brand? what brand do you recommend?

Answer
I have seen enough dogs, thousands, doing well on common brands such as Pro Plan and Iams, to know most dogs will do fine on them.  I frequently see questions here like yours, whose dog is having problems on a premium chow.  ''Stay away from premium foods and special diets like lamb and rice or turkey and barley.''  That quote is from the manual from a large dog guide school that breeds and trains about 300 dogs a year.  They can't tolerate problems like you are having.  

As far the dog not eating goes, the most common reason for a healthy dog not to eat is being overfed.  See http://www.longliveyourdog.com/twoplus/RateYourDog.aspx  Once you adjust what you are feeding to bring the dog into ideal body condition, chances are it will go ahead and eat what it needs.