8 yr old has Bubbles in her tummy and back of the throat

One of my 8 yr. old twins all of a sudden started with what I thought and doctors thought was a gas problem, I think its more than that, She says she feels "Full", "Bubbles in her tummy and back of the throat" and a "sweet taste".......She passes gas, Burps but is still horrified to sleep at night. She take 150 mgs of Zantac and 1 Beano pill before eating, they do NOTHING.... can ANYONE tell me what else I can give her to prevent and ease this all?? She's too little to be going through all this, I have stopped giving her Dairy foods and Gas causing foods. TYVM!!

UPDATE: She is now not eating or drinking out of fear that she will vomit and DIE in her sleep!

Plz, any advice would be appreciated.