@Pistol Thanks for your response. Doctor who believed me and suspected POTS was great, because of him my diagnosis was confirmed. But he said that he doesn't want to interfere about treatments and sent me to another doctor. And that doctor was not interested much in helping me. I have visited and contacted a lot of doctors. I don't know where elso to go in my country, noone from doctors is not interested much in POTS or they sadly think the "cure" is to drink plenty of water, eat more salt and exercise. I have tried some POTS tratments that didn't unfortunately worked. I will do some additional tests on my own and see if something else come up. When I got diagnosis I was so happy, I thought ok it's finally over, but then new problems arose, it's neverending story.