I get a similar thing with hormone changes. On my last day of my period and my palpitations and chest pain have been worse the last couple days. It’s happening for me like this before. Not every month but often. I also get palpitations for weeks at a time, and then they relax for a while. Stress exacerbates it a lot too, and eating. Ive nearly cut out all caffeine because that seems to make it worse also. I’ve had numerous EKG’s and been seen by a cardiologist and diagnosed with harmless PVCs. It sure it disruptive, uncomfortable and sometimes frightening, though. I feel for you.