I'm sorry to hear your pup has a hard time keeping food down. That's sad!
Do you mind me asking what type of food you feed her? I was going to suggest boiled chicken as a treat and maybe banana. Those are generally easy on the tummy. Apple can be acidic and cheerios may not work if she does not do well with grains. The Natural Balance biscuit probably won't do her well since she has such a sensitive belly and they might have wheat in them. But you can always try them.
-Snick & Viv