You were doing pretty well right up until you mentioned gluten. This near fanaticism with avoiding gluten is approaching the same level of thinking organic foods are more nutritious.
A restaraunt my wife frequents has completely separate grills and utensils for gluten free cooking. That's pretty much fanaticism.
Gluten has replaced peanut allergies as the allergy du jour. If you have celiac disease, you have a real gluten allergy. If not, not as likely
Gluten comes from certain grains.
Specifically, it's the protein portion of the seed. And each version of gluten is a little different. Anin in an ironic twist, is one of the meat substitutes for vegans.
Despite this fact, I have seen products, including fruit itself, labeled as "gluten free" which do not use grain in their production.
I saw a bottle of spring water that was labeled as "gluten free" As the wise man once said "No shit?"
Symptoms that have been attributed to gluten sensitivity include diarrhea, abdominal cramping, bloating, headaches, fatigue, and even those associated with attention deficit hyperactivity disorder (ADHD).
Sounds like a night of drinking cheap wine will cause a gluten allergy.
A real gluten allergy like Celiac disease will have some of those symptoms you described, certainly people with celiac know something is really off within themselves.
But it isn't common at all.
I'm more inclined to think that some people who eliminate processed wheat products from their diets might be eating better in general, might have taken off a few pounds, and if a person is overweight, taking off a bit is a great way to feel better.
But I fear you have opened a floodgate of criticism, we'll hear about how gluten allergies are caused by (insert trendy bugaboo word here) and that you're being an insensitive clod, and a ton of testimonial on how someone cured their gluten allergy, and will live forever because of it.
But don't worry, they'll move on to the next ailment du jour shortly.