Sachita, i am so sorry you're facing a hard time.
i have a bullie who has a very sensitive stomach and will throw up if he eats the slightest bit of anything other than Natural Balance potato & duck. The past several days, he has been eating less and has thrown it up a time or 2 (at least he always goes to the same spot to throw up).
Any suggestions on another sensitive tummy dog food i could try now that it seems like he's developing issues with his regular food?