Hello and thank you for using HCM. I carefully read your question and I understand your concern. I will try to explain something and give you my opinion. This fluttering sensation has to do with some electrical issues in the heart. The electrical issues might be different. It might be a simple sinus tachycardia meaning that your heart is beating over 100 beat for minute and you feel your heart fluttering. It might be a different arrhythmia, like atrial fibrillation when your heart runs in a chaotic way. I don t think it is your case. Or the fluttering sensation might be what we call an extra-sistolik beat, that is a premature heart contraction during its normal rhythm.This are quite normal in young people with normal hearts. All these rhythm issues might give flutter sensation, chest discomfort or pain, anxiety, difficulties in breathing deeply. The cause might be different from simple emotional stress to excessive coffee consumption, alcohol. It is important to avoid them during this time. The other cause might be pathologyes like anemia, hyperthyroidism, cardiac anomalies. So, if i was your treating doctor i would do the same that your doctors has already done, a rhythm holter monitoring. It will give a fool view of your rhythm tendency and show what are this fluttering sensations. I will also recommend a blood check up and your thyroid hormones. After this we can better judge what to do. Hope I was helpful. Best regards.