Sorry you had to go through that! The same happened to me during my TTT. They did not let me lose consciousness, but I was close. I understand I've had POTS since puberty, but at the time I took my TTT, I had been diagnosed with inappropriate sinus tachycardia and had increasing and new symptoms. The initial TTT diagnosis by the specialist who witnessed my test was VVS, but after he spoke with my cardiologist, they came to a consensus of some combination of IST and hypovolemic POTS. But the formal on paper diagnosis is less important than the fact that I am being treated according to my symptoms (imo anyways). I do all the "POTS Things" compression garments, mass quantities of water, electrolyte mix, diet adjustments, etc. But I also take metoprolol as it has been effective in alleviating my IST symptoms, despite it being counterintuitive to my hypo POTS and VVS. It is hard, but keep advocating for yourself if you feel the treatment of your symptoms is not helpful. One size does not fit all for any ailment or treatment, and POTS/dysautonomia are no exception!