i'm a 21 yr old male and been dealing with stomach issues for awhile, awhile back i was having chest pains so i went to the doc and they did blood work, echocardiogram, holter monitor, and a stress test and they said that all the tests came back completely normal. here lately ive been having some chest pains again kinda like a dull constant pain that comes and goes right by my left titty where my heart is, and sometimes i can feel like a hard pulse like twitch kinda in my neck and it makes me feel weird. and when the pain starts ill sit there and feel my pulse with my fingers on my neck to see if its beating right and ill scare myself and my heart starts racing and i start feeling worse. any ideas? could there be something wrong with my heart that any of those tests wouldn't have detected or would that be pretty much impossible?