chest pain on a 11 year old

my 11 year old son has been telling me he has chest pain and that his heart is beating very fast and that he has a pain that starts in his stomach and shoots all the way to the back and that his ribs hurt him.  I took him to the ER he had all kinds of test done to him they all came back negative.  Yesterday I got a call from his school that he was feeling really bad and if i would give permission to take him to the clinic that is located in the school campus (my son attends schools 15 miles from where we live) to make this short I found my son with oxygen mask and in real bad pain still complaining of the same thing this time he was haveing a hard time breathing as well.  I dont know where to go now because I was told the same thing he has acid reflux. Would anybody out there tell me the steps to take so I can take care of this before something worse happens.

[Encephalomalcia]

Acid reflux can be so bad that a person has a hard time breathing and in fact cannot walk for awhile because of it.  I was shopping one day when the acid reflux hit me and I could not breath very well and it stopped me.  I had to stand a few minutes holding on to the shopping cart.  There was no way I could even attempt to move.  I could not breath well and felt like I was smothering. It was acid reflux causing all of this.  Did his doctor prescribe medicine for acid reflux?  If the pain is shooting from his stomach, the cause most likely would be coming from his stomach.  If this does not resolve with medication, he will most likely have to have his stomach looked at (endoscopy).