Re: 18 years and, fainting...chest pains
tomas111: This isn't normal. The first thing that comes to my mind is: Are you eating enough? Have you had your blood sugars measured to see if you're hypoglycemic. Having low sugars causes dizziness. You might need to have an EKG to make sure there's nothing wrong with your heart.
I just saw recently on Dr. Oz where kids are colapsing and dying and after an autopsy is done they say it's Sudden Cardiac Arrest.
You should also be tested for asthma and lung issues. Do you smoke? If you do, that's not good. It constricts the flow of blood through the veins.
See if you can see another doctor and get some better advice. What do your parents say? I hope you've shared this with them so they can get you some help.
Don't give up. There's help out there. You just have to keep looking unfortunately. Doctors don't know everything all the time. You could also see a heart specialist. Good luck.