my heart all of a sudden started racing and pounding and it went away in likes 20 minutes

You need to see your GP about this. 

 

I have a tachycardia syndrome (fast heartrate) that I see a cardiologist and electrophysiologist of the heart for as it is usually not normal to have a faster than normal heartrate, especially after such a short time exercising.  How is your heartrate when you are at rest?

 

Your doctor will tell you if you have any chest pain then you need to go to the ER to get immediate attention to your heart and make sure that there is nothing like a stroke or heart attack going on or any heart damage.  They will take blood work and do a xray; that's about my experience, now I don't go anymore as it's a waste of my time.  I don't know about the heartburn but this is another reason why you need to get checked out and see your doctor or go to the ER.  Do you notice any pain going down your arm?

 

It may be nothing and it may be something but you need to be seen to get it checked.  Anything to do with your heart always needs to be checked out, don't wait.

 

Good luck and post back - don't hesitate with questions if you have any

heart problems is very serious to deal if problem is in heart since it is the sensitive part of the body always one should have to be in consult with the doctor so that the problem should be under control

No pain in my arm but little in my chest but I have a appointment scheduled for tomorrow

My heart rate at rest is 81 beats per minute

any problem regarding heart it is advisable to consult regularly to the doctor for better result

Forgot to add that I'm 15

Let your parents know as you may have a family history of heart disease even without that you need to see a Cardiologist to get to why you had a few episodes of this and continuing? You are concerned so see your doctor.