As all my tests are normal, what could be the cause for my palpitations and chest pain?

Hi doctor,

I am 18 years old. I have been a competitive athlete in my whole life. About a year ago, I started experiencing palpitations, near syncopal episodes, and chest pain. I have seen three cardiologists. I have had a bicycle stress test, limited echocardiogram looking at just the thickness of my heart, and also multiple EKGs. Before four months, I had a cardiac loop recorder implanted. All the tests have been normal. I have also had a workup in many other systems of my body including, endocrine, neurology, pheochromocytoma, kidney circulation and multiple blood tests. All came back normal. I am experiencing that my toes were becoming either white or purple, numb and very cold. My heart rate increases with minimal activity. I also have a past medical history of Goldenhar syndrome. Before two years, my second cousin passed away at the age of 13 due to an anomaly of his left coronary artery. My doctor has tried to order a stress echo and also either an MRI or a CT scan of my heart to check for this. I am looking for answers or suggestions on the next step.