I have a few chronic illnesses. Individually I think they’re at least easy to explain, if not something people already understand, but trying to communicate the combination is hard.
None of them are usually that bad by themselves. Together the issues compound and make it extremely hard to attribute symptoms to something specific. Like, are the migraines a rare symptom from a condition, a result of them interacting, one of the medications I’m taking or a new issue? I don’t know.
And when you’re vague (as in, don’t pull out your entire medical record and attribute each symptom to a specific condition) or the issues sound too severe for what people already understand, you get some pretty… negative reactions. “My uncle had X and he was fine, you’re milking it for sympathy!” but did he have Y and Z as well? Did he have the same variant of X? Was he actually fine, or did you never really talk to him about it? It’s rarely apples to apples comparing disabilities but that’s how people a primed to react.
I’ve learned to deflect and fall back behind medically privacy in professional settings, but it can be stressful.