Celiac Disease Support Group
Celiac disease is an auto-immune disorder of the digestive system that occurs in genetically-predisposed individuals. It is characterised by damage or flattening to all or part of the villi lining the small intestine, which interferes with the absorption of nutrients. This damage is caused by eating anything with gluten (gliadin), a protein found in wheat, rye, and barley...
Cross-contamination can take many forms, such as using a toaster that had been used for gluten bread, or using a cooking pot or pan that made a gluten product, or cooking GF pasta in water that was used to cook gluten pasta, or "double-dipping" a cooking utensil from gluten food to GF food. Many people cannot even use plates that held gluten food unless the plates were run through a dishwasher. Hand-washing dishes doesn't always clean well enough.
Hope that your son is beginning to feel better by now. Best wishes to you both.
Also, something that I have discovered, a glutening symptom can change as the body heals. At 8 years into this I find that an accidental glutening does not make me as deathly ill as it did in the beginning. Where I used to be violently ill now I would have minor tummy upset. Which is good and bad! Good in that an "oops" won't set you months back. Bad in that you can get a false sense of being able to tolerate gluten and/or not knowing that you did ingest some.
Hope you son heals quickly