SVT And Treatment

I am Sankar ,27 years male, working as a sales man for a pharma company, from the age of 17 I am facing a problem of high heart beat it starts at any time suddenly and with in 2 to 3 minute it comes to normal, but when it comes to normal i swets a lot leaving a stretching feeling of heart muscles, all these year i ignored the problem as it never effected in my daily life and i used to think as it common to every body. but last week again when i faced the same problem I thought i should goto a physician and i went to a physician he told  it is SVT, and he took a ECG test in which it showed normal heart beat and he told that the root cause can be found only when the ECG can be done when it occurs again. and also told not to be worry much, I just want to know is this very serious shall go to a cardiologist or shall change in my diet and daily activity suggest me, more importantly i don't take alcohol,I don't smoke then why only with me?