Hi, I'm 14 I use to have chest pains all the time that lasted over 20 mins or so i had chest pains since i was 9.(i've grown out of them now & i'm sure u will too)
When i did get chest pains all my ecg's came back fine though.
But do not worry too much, anxiety
can cause a lot of chest pain or being stressed about something. I use Gaviscon
still (peppermint capsules) u can get them on ur prescription for Free.(there r all forms of gaviscon, tablet or liquid)
Here is a pic of gaviscon cool: these r a bit cheaper & r sold in poundland(99p store) & superdrug: http://www.gaviscon.co.uk/images/products/gaviscon_cool_handy_pack.jpg
Good luck & best wishes