We do like these doctors - they are the second office we've seen since we moved. We do have a recommendation for another set of doctors so I'll keep that in mind.
He is not suddenly drinking more water. He'll drink several glasses with each meal (normal, and I do as well) and isn't asking for much in between meals unless he's been running around a lot. I'd be shocked if he was diabetic.
I did change him last night before I went to bed. He was still wet this morning but it didn't go through his pjs and drench the whole bed. That at least was an improvement. If I ask him if his tummy hurts he says yes but will not otherwise say anything about it. He does still look bloated most of the time.
I am not truly gluten intolerant - it's related to my chronic illness - but since I think that he also has this genetic illness going gluten free for him as well might be the next step (he is gluten free usually at dinner and lunch since I only make one meal for those but his snacks are not gluten free usually). I do wonder if I should push for an x-ray or ultrasound at this point, though.