In my case, as long as I was ingesting gluten, I had pain, discomfort, and irregularity. Once I went gf, if I accidently ingested or got cc, my reaction was much more "explosive" if you get my drift.
I hope your son can come around and go totally gf and improve his health. There is only so much we can do as parents. Once he realizes how much better he feels, it will make it easier for him to follow the diet.
Hang in there!
Jon, Co-moderator for Crohn's Disease, Depression, & Celiac Disease forums
"The man who insists upon seeing with perfect clearness before he decides, never decides. Accept life, and you must accept regret." -- Henri-Frédéric Amiel (1821-81), Swiss philosopher, poet