I m a 19 year old female and I excerise everyday and my blood pressure is perfect. My heart has fluttered on and off for the past few years but the past two weeks it has done it a lot. I do have a lot of stress and anxiety often which is why I work out. I m worried that I have heart problems. I m not overweight. I weigh 110 pounds. I ve been to a cardiologist but I can t remember if I told him about my palpitations. He said my heart was perfect and even did an EKG but that was 3 or 4 years ago.
Mostly the symptoms you describe are an attribute to your anxious nature, with exercise or any exertion the pulse of even normal human beings increase, now if you anticipate it you may feel it as the flutter in your chest wall.  Trying to divert your mind away will help.  However, if symptoms persist, get an EKG done at the time of symptoms, or if that's not feasible a 24 hour holder if the symptoms happens at least once daily Regards