The Pediatric GI did the endoscopy today and showed us the scalloping on this small intestine. He said he doesn't really even need the biopsy back to tell that he has celiac disease.
His appetite has improved so much that I have to imagine this is what kids his age are actually like.
My son was eating so little and was so cranky, that we saw a huge turn around in a week on the gluten-free. I'm glad the pediatrician had us do that even though we might not get a positive biopsy. Since most of the visible signs are there, I'm pretty sure that's the diagnosis we'll get.
I appreciate all the feedback!