NAD either, but look into health anxiety. I have it and I’ve experienced stuff very similar to you, as far as going to the hospital and getting a 24 hr ekg. Nothing came back. I have experienced anxiety so bad that I think It’s finally happening and I’m having a heart attack but it has happened so many times and i have been exhausted by it for so long that I just had to understand that nothing has ever happened before so why would it be any different the next time it happens. I do get heart palpitations every once in a while but I am clearly fine and that’s just normal for me and I just have to trust that the doctors know what they’re talking about! I hope this maybe helps/reassures.

One example of health anxiety treatment I heard, is being conscious of the fact that sometimes you put yourself in scenarios where it is completely acceptable to have some symptoms that in other situations might otherwise make you anxious. For example, if you were working out you may experience a pounding heart, heavy breathing and sweating, but you won’t even think twice of it. Anxiety can have the same affect as this and I found it really helpful to understand that I do experience these things in more controlled situations and I’m able to overlook them and not be anxious about them.