Is he nursing (grin poop- formilk hind milk issues) ? Just hitting major milestones (extra calories for extra activity)?
Honestly Celiac isn't the first thing that would pop in my head with that. Now with the IgA deficiency that does throw a monkey wrench into things. Being positive for the gene isn't really that telling for anything other than that Celiac is a POSSIBILITY.
Give what you told and the desire to redo the scope, I (as a Mom) would not change his diet. If they are going to re do the scope AND redo it PROPERLY ( 4 samples are not sufficient) I would much rather it be done correctly while on a gluten containing diet.
If all the other tests are good and there are no vitamin deficiencies or anything going on I would really not change anything till there was a proper scope. Take that from someone who is basically living this now after 4 years on the gluten-free diet and there still being issues BUT also follow your gut Mama!!