Heart palpitations. Diziness as such.

I've been having heart palpitations since last 4 years where I experience flutterations, pounding and sometimes racing for no reason even if there is no physical activity involved. I experienced this problem for the first time during a cricket practice session few seconds after I started jogging and since then it has persisted. It leaves me in panic whenever this happens and I'm concerned about my future. Most of the time I don't give attention to this and my heart beat will be stable and all of a sudden it starts racing inspite of staying relaxed, because of this I've quit playing sports and took up yoga it has help me to extent as I focus more on breathing techniques. My first ECG report showed 122 beats per minute and doctor advised me not to stress too much but after few months my mother passed away, that exerted too much stress on me and incread my palpitations even more. But I have no chest pain and dizziness as such.