Nothing breaks my heart like children struggling with "health issues". I've had children with "health issues", and at times it has brought me to my knees. However, we must pick ourselves back up and carry our children as well.
You say "non-irritating diet"? I would think that means the normal gerd diet, ie; lean meat, veggies, whole grains, no choc., soda, red sauces, spicey foods etc... Does she sleep on an incline? Manuka honey (teaspoon) with warm water is very soothing and it taste good so it may be easy to get her to drink it. Going with a bland, low fat diet and taking digestive enzymes before each meal will greatly ease the burden on her tummy.