Noah just started Prevacid a little over a month ago, and was taking zantac for a few months before that, but not for the reason listed by others on this post: he was, unbeknownst to anyone, aspirating food into his lungs. All the meds he takes increase his acid production, which was causing reflux. He never complained about it or anything. When you mentioned high-fat foods causing the burping (and farting) my first thought was that's what was happening to Noah before he started the Zantac. The aspiration was discovered when he had a bronch late last year.
Also, a tip about outtings and enzymes:
If we know we're going to be out and about for a while, and there's a high likelyhood we'll be eating, Noah has a backpack he takes with him that has enzymes, rescue inhaler, a snack, and something to occupy him in the event of a wait. In the event we eat and don't have the backpack, I also carry a smal pill bottle in my purse w/ enough enzymes for 4-5 meals.
Hope this is helpful.