From what I understand, POTS could well be secondary to UARS. (It is known to be secondary to many autoimmune conditions, CFS, COVID, etc.). As far as I know, checking for POTS is not part of a standard “mystery fatigue“ workup (like checking thyroid, iron, and vitamin deficiencies), but it should be, because it’s common, particularly for young women between the ages of 15-50.
I’m having to wait until November for surgery and have been desperate to find relief (I‘m elevating the head of my bed, using breathe right strips, a nasal spray, etc.), so I was both surprised and (weirdly) very happy to discover that I have had POTS (postural orthostatic tachycardia syndrome) since I was a teenager and that it is easily managed with compression tights, dramatically increased salt and water intake, and a fairly short cardiovascular rehab program (around 6 months) that begins with recumbent exercise and goes from there.
Even just wearing compression tights and increasing fluid + salt, I have felt so much clearer cognitively and have far more energy. Such an answer to prayer.
POTS (and orthostatic hypotension, another form of dysautonomia) can be tested for at home with a BP cuff using the NASA Lean Test (often doctors use this test to diagnose patients, though a tilt table is the gold standard). Obviously, see a doctor before dramatically increasing your salt intake, but while you are waiting to the doctor if you confirm POTS there is no harm in wearing compression tights (waist high is most effective) and very modestly/conservatively increasing water and sodium.
A warning: if you have POTS, the NASA lean test could leave you feeling exhausted for 1-3 days. I had an extreme reaction (my HR jumped 70bpm, while the threshold is 30bpm increase) and was basically bedridden for 2-3 days.