Celiac Disease should not have pain involved - just major digestive issues, vitamin deficincies, etc. I was misdx with it when they were trying to figure out my issues - which they found out was Crohns because I had pain, and Celiac doesn't involve pain.
Celiac is very very common - but is grossly undx in the States. Most other Western countries have figured out how common it is and their doctors are able to spot it easily. We're behind the times, unfortunately. Many people have it and have no idea. Our foods are not friendly to Celiac patients, either, though that is getting better. More and more restaurants are adding gluten free menus. More and more grocery stores are stocking gluten free foods. It's getting better but one has to really be a good label reading - and yes, people are so sensitive that things cannot be cooked in the same place that gluten foods were. Or processed in the same factories. Some are not that sensitive.
There are several on this board with Celiac or have family members with it - I've spoken to them at length when I was dx with it.
In order to REALLY know it's Celiac, you need a biopsy of the villi in the small intestine. That is done through an upper endoscopy. There are no concrete blood tests that guarantee it's Celiac. My bloodwork pointed to that but it can also point to other things - like Crohns. Obviously, for me, it was Crohns. My biopsy was normal. When a Celiac patient consumes gluten, it damages the villi and causes them to shrink up. This prevents nutrition to be absorbed and other digestive issues. It's a step beyond a gluten intolerance. It can also be referred to as Celiac Sprue or just Sprue.
Common symptoms are gas, tiredness, bloating, weightloss, abnormal stools, etc. Most people have such light symptoms that they pass it on as IBS or nervous tummy and never get dx.
For others, switching to a completly gluten free diet proves to sold the issues, even if they opted to not do a biopsy or the biopsy came back normal. I ate gluten free and saw no change - so it was fairly positive that my biopsy was indeed right.
My prayers are with your baby boy - I hope answers are found soon and that they can give some meds to relieve his issues. I hate to see little ones sick =(