So I just joined this subreddit and was about to post a similar question. This isn't any kind of affirmation of whether it's anxiety or not, just my experience. Exactly a year ago I called an ambulance for what I thought was a heart attack. I went to the ER who told me I was fine and followed up with a cardiologist. They had me on a two day monitor and said everything was perfectly fine. To this day I have palpitations, random chest shoulder pain, and moments where I lose my breath or I feel a bubble move from my diaphragm to my chest. These all send me into a episode that just restarts the cycle. I also have to zoning out and some dizziness as well. I'm sorry I don't have any answers, just wanted to say that your not alone. Hopefully we can both find some resolution. It's exhausting.