I just had a laughing fit and I had a flutter in my upper chest, which felt like it went into my throat too. Do you know what this could be? Also, I ve had a pain in my left side of my chest and in the same location in my shoulder blade when breathing in and/or taking deep breaths. This wouldn t be the signs of heart disease will it, as I m only 20 years old, I regularly go to the gym, and I ve recently had a 24 hr ECG which came back normal, 7 standard ECG s which came back normal, and 11 blood tests which all came back normal. I had those tests as I had palpitations back in May 2012. Since May, I ve had lightheadedness and funny woozy spells, but after frequent check-ups from my Doctor, I was advised I was fine, and the bloodwork also showed no abnormalities. Do you know what this could be? Thank you!