testing321

hi there..im a teen and today i was lying in my bed trying to sleep..i cudnt sleep so i started stretching a bit while lying down...after sometime i felt that a pain arises when i took a deep breath (the pain arises on the left side of my chest below the heart)..i stood up and as soon as i try to take a deep breath i feel pain on my left area of the chest...i think right below the heart..now after surfing the web a bit as im typing the pain has vanished and im normal..i still want to know what problem i had..also this pain rearly occurs..i think last time it occured was a few yrs bak...ill apreciate any input about this situation...thankyou very much.