Heart Problem. The medicine or not?

I had gone on a tour some days ago and then suddenly my heart beat rate reached 150 which i checked at home by a blood pressure monitor....The food outside home is not liked by me and so I took food irregularly and so the blood pressure became very low then I rushed to the nearest superspeciality hospital and consulted an cardiologist , they immediately transferred me to the EMERGENCY CARE where they increased the blood pressure and lowered the heartbeat......They conducted an ECHO-CARDIOGRAPHY and ECG before this but it was normal.....Then Doctor prescribed me Seloken XL 25 mg medicine....This happened about 1 month ago.....The doctor advised me to take the medicine at 8 am daily and due to this medicine,i think, my hand and shoulder pain comes.....and i am getting fatter slowly.......For the last 3 days I am not taking the medicine and in these 3 days no problem of heart is seen.....Now what to do?? should I continue the medicine or not?