At first I thought it was traped gas so I took 2beano waited 5min and it didn't do any thing to help so my husband got me another one still did not help.The tightness was just above my sternum in the center of my chest,my heart was not beating fast at all,I always have a fast heart rate and I can always look at my wrist and see my pulse but I couldn't see it.I could only take shallow breaths I felt like I wasn't getting enough air.Then the tighness felt like it went through my chest into my left shoulder blade.I was cold but sweating..this lasted about 45 minutes then it went away.I felt like my self for a hour or so after the symptoms where gone but then this over whelming weakness and tiredness came over me.I slept the majority of the day.Today I feel better my heart is just beating really fast...What could this be?