IDK what i have? Heart Pain, Irregular Heartbeat.. HELP? Earlier this week on sunday i was in the car with my boyfriend and i had a severe chest pain. it felt liek a squeezing but that was it, no shortness of breath or anything. it lasted for about an hour then just stopped. i felt fine. Monday in my computer class it happened aagain but worse. so i went to my school nurse and she gave me tums thinkin it was heartburn, it wasnt, so she checked my heartbeat and noticed it was irregular.
i went to the doctor then to the hospital and had a bunch of tests done. so far nothing. they thought it was diabetes but that came back negative. 
i was just wondering what are some possible diseases i could have?
im just kkinda nervous and i dont like waitin for the doctor to call.
please help;
im female, 16 and slightly overweight
if that you needed to know.

Summarized question: What could cause chest pain in a slightly overweight 16-year old female?