Reflux nonresponsive to Prevacid, Zantac and Prilosec

My son, 7, has been dealing with reflux for at least last six months.  He was diagnosed with relux when he was two with a barium swallow.  It either got better or went away completely with treatment on Zantac at that time.  Now it's back and the meds. mentioned above have done nothing to help.  Sometimes the relux is the typical sour digested stuff and at other times it can be a whole undigested bit of food from a meal 4 hours ago.  We are on week 4 of Prevacid 30 mg, after having unsuccessfully tried a Prilosec at 15 mg, which was not effective.  I just feel so bad for him, I don't feed him spicy food or tomatoes, no caffeine and very little to any chocolate.  Yet it seems it doesn't matter what he eats, he will be tasting it again anyways, ham and cheese sandwhiches, mac and cheese, cereal, watermelon, cantelope, you name it,, he refluxes it.  Thank goodness he is not loosing weight but his beath is so often sour throughout the day and many times during school he just swallows the reflux instead of spitting it out.

I am just wondering what should be expected next?  Finally have gotten a Ped. Gi consult soon, and am expecting tests.  How common are hiatal hernias in kids?  Could he have EE, or a motility issue?   Any insights or thoughts as to what might come next would be greatly appreciated for this frustrated mom Thanks.