Not saying your symptoms aren't real. How do you know they aren't psychosomatic? For many (most?) people who "discover" such dietary things causing that kind of discomfort, it can be shown that the symptoms (very real symptoms) are psychosomatic.
I know someone who definitely experiences psychosomatic symptoms. A mere suggestion or suspicion almost always leads to 100% "confirmation" in this person's mind. Despite that, the symptoms are very real.
Could be argued either way I guess. Physically, I always had allergic shiners (dark circles under my eyes), pale skin (anemic), running or stuffy nose, mild eczema, etc. plus I just always felt like crap - no energy, constant headaches & migraines, had no idea it was food-allergy related, just lived with it for years unknowingly. I have since removed those from my diet & all that stuff went away, and if I eat it, it comes back. I would say there's probably a 4-way split with food allergies:
1. People who are severely allergic & have to go to the hospital or take an Epipen, or get super-sick (ex. Celiac's)
2. People who have an intolerance - you don't die, but you feel like crap. Sort of like the difference between people who get stung by a bee & die, vs. the people who get stung by a bee & swell up like a balloon (as opposed to people who just get a small red bump), but don't die.
3. People with suggestion-based psychosomatic "allergies" who have a strong belief that X, Y, or Z causes symptoms in them. This is probably the same group who are sensitive to microwaves or wifi signals or whatever. Healthy food nuts are also in this category...Jimmy Kimmel did a hilarious experiment where he made juice out of Skittles & Tang and marketed it as like non-GMO freshly-squeezed juice & people were totally buying into it:
https://www.youtube.com/watch?v=75b2hTl2T2E
4. People who do it to be, ah, "special snowflakes", either for attention or for weight loss purposes, or for some kind of vague health benefit.
Part of the problem is that our medical technology is not good enough to diagnose everything yet. For example, I don't react to any medical testing for dairy - skin-prick test, blood tests, etc. But if I drink milk, within minutes I get severe nausea, black circles under my eyes, tongue gets coated white, etc., and this happened growing up, before I made the connection to food as a cause, so it's not like someone said "this has milk" and
then I went into a 'reaction', I just felt like crap constantly & didn't know why. But it's not like we have an off-the-shelf test for diagnosing a headache with a blood test or something, so it's really hard to make the correlation between an internal reaction & a food allergy without simply doing an elimination diet.
I'm sure at some point, they'll figure out more advanced testing methods, but it's also important to realize there's different groups - people who need attention, people who are hypochondriacs, people who are sensitive but not deathly allergic, and people who will basically die if they don't get treatment ASAP. So it's not like it's just one lump category of "it is or it isn't" because it's not that clear-cut. If you personally feel fine when you eat say gluten or dairy, it's easy to jump on the Internet bandwagon of "a gluten intolerance is fake!", but that could just be because the person you've been dealing with IRL who makes that claim is a hypochondriac. I've been to several top allergists & they've all said that the field is still developing & their tests are not very accurate yet; stuff like peanuts or dairy that cause an immediate skin or anaphylactic reaction are very easy to diagnose, but the rest are not. I'm sure someday the technology will advance, but we're not there yet, so that combined with the different levels of allergy (whether it's in your head or not) make for some interesting online discussion
😉