16 y/o with chest pains? Help me please!

Hey everybody i'm 16 years old i'm a male and i've been in great shape my whole life. I've been playing football since i was 5 and i can run like the wind without a problem, i lift weights and never really eat anything all that unhealthy and if i do my metabolism burns it off. About 2 weeks ago i started getting random chest pains through out my chest but mostly on the right side either towards my collar bone or down to the right a little to the left of the arm pit area. This pain is very intense however it only lasts for a minute and a half or so. Along with it i get a little sweaty and very dizzy. I can feel my heart beating inside my chest for roughly 5 minutes after it happens and then i seem to be fine again until another one of these random "attacks" so to say, happen. I've been the the emergency room 3 times because the first thing that came to my mind obviously was "OMG I THINK I'M HAVING A HEART ATTACK" well it turns out that all 3 of the times i've been to the hospital everything has come back positive, EKG, Blood test, X-rays, EVERYTHING. I plan on being in the marine corps in 2 years and i really don't want this to set me back. I have a doctors appointment with a pulminologist (respiratory doctor) this upcoming monday but i was wondering if anybody had any idea what they think this might be before i go and see my doctor. I'd like to add again that these pains are very intense and it feels like my heart is about to jump right out of my chest, i also get pains that go up my neck and down my arm on the right side when this happens and i start sweating profusely. I would also like to mention that i have a significant amount of stress in my life, My mother has severe fibromyalgia and on some days is barely able to function which means that i must keep on eye on her CONSTANTLY, My grandfather who i was very close with has also passed within the last week and i'm thinking all of this stress may be getting to me but i'm not sure, Any advice or info would be great! thanks!