My daughter is 16 & has been complaining the last couple of weeks of her heart having a flutter or palpating happening with shortness of breathe. ?

See doctor: Even at such a young age, she can have some heart conduction (electrical) abnormalities. She needs to have that ruled out first . If all normal, could be anxiety related . Please see a doctor soon

Needs evaluation : the symptoms you described should be evaluated in person by a physician. Start with your pediatrician who will eval and then likely refer to a cardiologist for an EKG or a pediatric ER can also accomodate you.