URGENT. should i be tested?

context: symptoms have been going on since early teens. ♡ when i exercise my heart rate easily goes into the 200s, i have crazy heat intolerance, CONSTANTLY exhausted no matter how much i sleep, fainting like a mf weekly, dizzy and light headed, have done competitive team usa sports and dance for years and still exercise frequently but feel nauseous and black out after the simplest stuff still (healthy diet and not overweight), always out of breath, constantly feel the need to be lying down/sitting even, always black out when blood is drawn, got blood work done and i’m anemic but not crazily and have high triglycerides and high cholesterol (mainly meat dairy and sugar) yet i’m vegan and eat healthy. did an ekg and ultrasound for my heart and everything was good. repeated a year later and was still good. i asked about pots a couple years ago and was told to eat more salt and i’ll be fine, he said i probably have an orthostatic disorder but did no additional testing. someone pls help i can’t keep living like this