Almost forgot my heart rate has been going at least 10 BPM faster than usual all the time even at rest.
I think you should try the beta blocker. Metropolol works best if you take it every day, maybe at 25 mg or less.
If you wan fast acting then perhaps Propranolol is for you. It works within 30 minuttes max.
Metopolol can give side effects but it varies individually. I got nausea and cold feet and tiredness.
Nevibolol is another new beta blocker, that has fewer side effects, as Im speaking of experience.
Metopolol will probably work for 24 hours and yes then the symptoms come back, and if you take them for many months, then you can expect more palpitations for a few days.
This is just my personal experience.