Living with chronic orthostatic intolerance

Hey everyone, I'm Giga, and I was wondering if anyone here knows anything about chronic orthostatic intolerance—it’s one of those diagnoses that the American medical establishment and our doctors seemingly refuse to acknowledge exists.
The symptoms include losing your balance, nausea, vomiting, and tachycardia whenever I move around, which basically means any kind of movement can trigger it; sometimes just bending over is enough to make me feel sick to my stomach and start vomiting.
Around here, doctors will only recognize standard orthostatic intolerance, but let me tell you, that isn't the same thing at all!
Does anyone else out there dealing with a similar diagnosis or struggling with these exact same issues, where your doctor hasn't actually given you a definitive answer yet and instead keeps dragging you through endless tests, none of which seem to specifically address COI?

bok Giga!!
I’m dealing with some pretty similar symptoms, just without the vomiting part. Every time I stand up, my heart starts racing like crazy—hitting 150 bpm easy—but once I squat down or lie back down, everything settles right back to normal. My doctor is convinced it’s just orthostatic hypotension, but honestly, I’m leaning toward orthostatic tachycardia, which is one of those things most American doctors don't even bother looking into. Have you actually managed to get this sorted out? If you have, please tell me how!