Hello and thank you for using HCM.I carefully read your question and I understand your concern.You shoud not worry . I ll try to explain you something and give you my opinion . As you describe your symptoms seems to be related to rhythm issue. There are some electrical impulses that generates from different parts of the heart different from normal sinus rhythm.They cause a premature heart contaction that its not a normal one followed by a pause and than a normal heart contraction.This are what we call extra sistolic beats. You might experience palpitation, flattering or this bubbling sensation, difficulty in breathing deeply. If this happens once in a while you should not worry, its normal. Only if this begins to interfere in your daily life I would recommend some examination like an electrocardiogram , a cardiac echo and a holter rhythm monitoring to have a full view of your rhythm. Also a blood analyze and your thyroid hormones. After this we can better judge how to treat this problem. In mean time avoid caffeine products, energy drinks becouse they exacerbate this symptoms. Hope I was helpful.Wish you good health. Best regards.