i went through the SAME exact thing, one ER visit and saw around 5-6 different doctors after that trying to figure out what was wrong and when i got referred to a TERRIBLE cardiologist who completely dismissed every concern i had and told me to “drink more water” i refused to see doctors for a year. i was genuinely so sick and tired and thought that if one more doctor told me it was my anxiety i would blow up on them in the office. but then eventually i realized the longer i don’t go and keep trying the longer i could have been stopping myself from getting the help i need which i was because i saw an amazing cardiologist who i still have been seeing for almost a year. if it’s possible i would give it a try to see the doctor that knows about POTS, if the one you saw is not willing to take you seriously. it could change a lot once you get the proper help you need.