Hello! Thank you for asking on HCM! Regarding your concern, I would explain that this feeling looks like a paroxysmal cardiac arrhythmia (an episode of atrial fibrillation or flutter, frequent ectopic beats or even ventricular arrhythmia, etc). There is only one way t oconfirm any possible arrhythmic events, by means of ECG registernig during such unpleasant feelings. The most appropriate option would be to undergo an ambulatory 24 to 48 hours ECG monitoring (Holter test). In addition I would recommend you to perform a medical check up by your internist or cardiologist, for a comprehensive physica lexam, a resting ECG, chest X ray study, some additional lab tests like complete blood count, PCR, Thyroid, liver, renal function tests, blood electrolytes, etc, to rule in/out any possible flu complications, like thyroiditis, pericarditis, myocarditis, etc. that may lead to generation of cardiac arrhythmias and altered overall health status. A cardiac ultrasound would be necessary, if suspicions of myo-pericarditis, etc are raised. Hope to have been helpful! Greetings! Dr. Iliri