Possiblity of GastroCardiac syndrome?

I am a 22 year old male, 140lbs 5'9, Asian. I am residing in the USA, no drug use/smoking. I am currently visiting a cardiologist, and they noticed an abnormal heart rythmn + higher blood pressure (140 when sitting, 160 when lying down). EKG shows voltage spikes are twice that of the average person. Echocardiogram is perfectly fine, and Holter monitor shows no arrythmia. We are doing the treadmill stress test soon. In high school, I used to be decently athletic, but my health took a nosedive soon after.

Starting from the very beginning of the pandemic, I had sudden energy crashes with fast thumping heartbeats (over 90 pulses per min when sitting down). These energy crashes occur almost everyday, I often get knocked out into 2-3 hr naps. These energy crashes would be triggered by eating heavier foods + more intense physical exercise, as well as if I feel any strong emotions such as anger. I also had a bad bout of GERD, but that faded a year later. I also feel a sinking pit in my lower left abdomen sometimes.

I visited an endocrinologist, gastroenterologist, and had a sleep study done. Everything was fine according to these doctors, no sleep apnea/narcolpesy, no thyroid issues, etc.

Do you know what it could potentially be? Could it be related to cardiogastric syndrome? Due to past stomach issues, perhaps it is effecting my heart as well via the vagus nerve.