[sandman1906]

Have you considered that it might be costochondritis?

I'm 23 and healthy. I went into ER a few months back with high heart rate, chest pressure, and palpitations. They couldn't find anything wrong with my heart, monitored me for a few days and discharged me without a diagnosis.

For 2-3 weeks after that I still had that same occasional chest pressure/tightness. This might be a coincidence but it started easing away when I started doing various exercises meant for costochondritis.