Hi, I'm a 19 year old with ME/CFS and POTS, a diagnosis I received when I was 14. I have been told by my doctor that my POTS is severe as compared to what she's seen in other CFS patients, and I definitely find it greatly disrupts my life, as I constantly feel on the verge of blacking out and tachychardia and irregular or thumping heartbeat keeps me up at night and is a scary and constantly uncomfortable symptom that I would sell my soul to get rid of. I take 20mgs of Indarel a day but it does relatively little to help. As I was diagnosed so young, I never learned much about POTS and have found what I've researched on the internet to be a bit confusing and contradictory (though maybe I'm bad at looking) So please forgive my ignorance but I have a few questions about it I'm hoping some kind folks will answer! 1) Do we know what causes POTS? As far as I can see, no one seems to know what it's caused by, but are there clear theories? How should I research it? 2) How does it relate to adrenal/thyroid problems? Is it just adrenal dysfunction that causes the tachychardia with the overly responsive nervous system? 3) What do people do to help relieve thumping/racing heart after exertion? Is there any way to minimise the symptoms? Thanks so much in advance!!!!