Unfortunately, you’re not finding any straightforward answers because allergies and non-IgE-mediated allergic reactions are poorly understood, even by some allergists. (usually the gaslighty kind 🙃)
It is entirely possible to test negative for allergic reactions for things you are absolutely having allergic reactions to.
This is because allergy tests focus ONLY on “true” IgE allergies and do not take into account that there are other underlying mechanisms that can cause mast cells to degranulate, which is what happens when you have an allergic reaction.
In an IgE reaction, the cells become unstable, releasing various hormones/chemical responses, which is what we know as annoying allergic reactions in minor cases, and anaphylaxis is severe responses.
In a functional immune system, these chemicals should really only be released in response to a true IgE allergy.
When your immune system is a little over-reactive, they can release in response to stress (this is what causes stress hives, and we now think some cases of IBS) and sometimes things like viral illnesses. This is why so many people have developed MCAS or MCAS-like symptoms after having covid. (mask up, besties)
Sometimes, however, the “off” switch in the immune system gets broken, and the mast cells become increasingly over-reactive, and that’s when you can start developing new or seemingly random allergies that are inconsistent and don’t show up on IgE allergen test panels. It’s why you’ll sometimes see the term “idiopathic anaphylaxis” in people who have anaphylaxis that can’t be explained. Well, the explanation is wonky mast cells. Why are they wonky? We’re not really sure.
Perhaps if the medical world hadn’t ignored its existence for ten+ years and focused so much on gaslighting patients until a mass pandemic hit, we would.
This type of mast cell degranulation, triggered by a non-IgE-mediated reaction, is common in histamine intolerance and mast cell activation syndrome, which can also be comorbid with EDS.
So are you reacting to things not showing up on an allergy test? Quite possibly, and your EDS makes it more likely.
Unfortunately, the testing for both is a crapshoot and are actually intended for mastocytosis. This is not to say you shouldn’t ask for a tryptase test (the 24-hour urine test is far more accurate than the blood test); I just mention it because it is entirely possible to have HIT/MCAS and still test negative for elevated levels of tryptase.
Until better testing methods are available, HIT and MCAS-aware doctors will now often diagnose based on patient history and response to mast cell stabilizers.
Anyway, sorry for the wall of salty text, I hope some of it is helpful to you! Best of luck with figuring everything out!