Welcome to the forum Cano.
At 16 you are smart enough to find this forum, but you should have a parent looking out for you. Remember that forums, including this one, are just a bunch of people off the street, not doctors. We have no medical education. We're just telling our experiences, which may have nothing to do with your situation.
I think you should go back to the clinic to let them know if the Prilosec is working. If it's not then they might send you to a couple of specialists, a cardiologist and a gastroenterologist, for further workup.
I had chest pain and tiredness after walking a short distance for a few years. Then I had a heart attack. I was older than you, but I was 100 lbs less overweight. I had arteries clogged by cholesterol plaque.
What was the result of your blood work? Did they check your cholesterol? If it's high you can still reverse the clogging effects by not eating bread and drinking sodas. At least that's all I had to do. It's not about avoiding eating cholesterol. Your liver takes carbohydrates (bread) and turns it into cholesterol. I hardly eat any wheat at all now and I can feel my arteries are cleaner than they've been for many years. My cardiologist calls me the poster child for lowering cholesterol.
I would suggest getting a regular doctor, a family doctor, not just a specialist. He will investigate ALL your symptoms, probably cheaper than a clinic or specialists. You need to see the same doctor most of the time, who knows your history.