Hi, Welcome to HCM, After going your history it looks you had episodes of Tachycardia which could be SVT( Supra ventricular Tachycardia) they come spontaneously and many times spontaneously resolve. You must check with your cardiologist and get ECG to see cardiac rhythm. Such episode may be transient hence may not be seen in resting ECG. A careful cardiological examination may reveal any abnormality,if not may be Echocardiography, TMT, Holter monitoring may be required. Once it is detected treatment will depend on cause, In some cases more advanced EPS (Electro Physiological study) may be required and treatment depends on result of such studies. In the mean time avoid smoking,or tobacco use and Excess of tea and Coffee, and just relax once cause is detected it can be treated. Please do not ignore these symptoms. Take care Good luck