Can a person 18 years having a heart attack ? Since childhood I have always had chest pains and sometimes they passed me and other dizzy numb left arm. The chest pains last me a few seconds to 30 minutes.
The combination of chest pain with numbness of the left arm and increased symptoms when you are most active seem to suggest heart problems . I think it should be tested that may be sensitive enough to pick up a subtle problem - perhaps a congenital anomaly of the coronary artery or a predisposition to a marked tachycardia ( rapid heart rate ) . The stress echocardiogram or Holter may be appropriate. I would recommend discussing this with your cardiologist.