I am 16 years old, I am feeling lightheaded, sometimes I get these slight chest pains & fast heart rate, I have had 2 ekg s, 2 chest x-rays & 2 blood samples. They all came back fine, what could be causing this? I m taking medication for GERD (just in case it is that) & cutting out caffeine. What could be causing my lightheaded feeling, slight chest pain, soreness or pressure & varied heart rate?