> as I researched my own fatigue and finding out I likely have this

Please don't do this. It's the medical equivalent of copy/pasting shit you don't understand from Stack Overflow.

Go see a doctor who has a degree and training.

As someone who has gone in to doctors for issues with fatigue, it’s incredibly draining (both emotionally and financially) to be batted around between a PCP and specialists that are unable to provide you with a diagnosis. I don’t blame anyone for just sitting down and trying to learn whatever they can by reading.

I agree with your general thrust of course, you’re much more likely to incorrectly diagnose yourself doing this than correctly, and walking around with a false belief is worse than walking around with uncertainty. But simply saying, “go see a doctor,” is rarely helpful. I’ve never heard of someone who tried to diagnose themselves without first presenting the issue to a physician.

Autonomic neurologists are the relevant specialists. I invite you to look for one in your local area and see how rare they are. The last I checked, the Seattle metro area (and in fact the whole state of Washington) had precisely one board-certified autonomic neurologist. Diagnostic delay is, unsurprisingly, around six years. Combine that with the fact that all the equipment you need to do a basic POTS test is a pulse oximeter and a blood pressure cuff, and yeah, you're going to have people self-diagnosing, for good reason.

If there's no test for it, then what is the doctor going to do for something as nebulous as long covid?