It's heart attack? What i do? Ecg again?

My age is 18 years old and my problem is chest pain in every night (in middle of the chest) recently (before 5months) i do it ecg ,2decho,xray and one blood test(i don't know which test) as doctor says me to do that and all tests are normal ecg & 2decho (doctor says your chamber is good condition )so i go for some(5months before) chest physician 1chest physician says it's gas related problem after taking medicine not effect on my problem so i go for another chest physician he said it's weakness in bone problem. I also taked Those medicine after few months now i again felling pain in chest and feels like vormit (sometimes feel like vormit) plz what is main problem plz give me suggestion which physician is best for this problem what can i do now ?can i do ecg again ?or give me some tips :)!!!