I currently smoke but am getting ready to quit again. I quit before and I had those same symptoms. It's kind of scary when your heart feels like it's getting ready to stop beating or beating out of your chest. It's just your body going through withdrawls and eventually will get better. Kudos to you for stopping and if you get wore down from it, just pray to God every night to give you strength to fight it. It isn't an easy thing to do and I'll be thinking about you when I quit in a few days. Good-luck to you and I wish you many healthy years!