thank you for your query.
Tachycardia or fast
heart rate need to be throughly checked.
She would need and ECG, Holter monitoring( and extended ECG for about 24 hrs to see how her heart beats for a whole day during her daily activities),
blood work to rule out thyroid problems and anemia which can be undertaken at a
primary care physician office( except maybe for the holter monitoring) and treated accordingly
Sometimes , in the conducting system of the heart ( nerve tissue responsible for passing current through the heart to initiate
muscle contraction with a preset late and rhythm) there be an additional loop or bundle of
nervous tissue that interfere with this conduction and introduce extra beats causing apparent tachycardia. this can happen paroxysmally( on and off).
if that's the case, she will be referred to a cardiologist for further evaluation and treatment option.
hope I've helped .
please feel free to get back to us if you need further clarification.
Wish you both good health.