Getting pain on below left side of chest

Im a student. From past 3 Days I started to Get mild pain on Below Left Side of the chest Near to pectrol gap but slightly left side but Near pectrol gap extending slightly to left side Exaclty There only Mild Pain. I dont smoke or Drink. I dont know whether its Because of acidity or Gas One year Back I done endosocopy because I used to get burning Sensation afterfood but The Report came Normal  said It was acid Reflex and Said to Avoid Masala Food.. as I used to stay In PG Hostel. Now I also Im staying in PG hostel but I Dont Know Whether its Gas or Acidity I was in Anxiety Regarding it  My Relative is a  Mbbs Told to E.c.g So I Done E.c.g I will upload it. Can you please Tell me Whether is there any problem or Just  acid Reflex or Gas or acidity in simple method.