I ak going through nearly same thing that you are. It has been going on for several years but recently escalated to alarming heights. I have an appt. next week with a gastroenterologist. What I have been able to narrow it down to so far is that some aspect of my digestion or liver is messed up. Anytime I eat anything (and I am very careful with what I eat), my stomach swells with painful gas, even before I am finished eating. This in turn irritates the vagus nerve, which is what is causing the racing heart, panic attacks, trembling, palpitations, etc. The problem is, my stomach is doing this 24/7, even when there is no food in it. I wake up with it in the middle of the night, in the morning, throughout the day I have it. I almost always have to have a bowel movement when it is at its peak (though it's only been diarrhea lately). It's like my vagus nerve is stuck in alarm mode, whichnof course stresses out our adrenals more. Incientally, the adrenals are part od the autonomic nervous system. Some aspect of our autonomic nervous system is out of wack. I highly recommend finding a naturopath who specializes in autonomic nervous system disorders. I found someone near me and will be seeing him soon. Also, check out this link: https://retrainingthebrain.com. This program was ctreated for people like us. I just ordered the DVD's.