Worried about heart attack/ heart problems

First of all some background info:
i am 16 years old, i exercise regularly (5 times a week: 3 days Interval running and 2 bodyweight training).i stopped doing exercise and started eating really badly (fatty foods, bread cheese all that stuff) about 4 weeks ago and last week i started doing the above mentioned routine again.
So 2 days after beginning with my routine again i started having some mild pain in my left arm, all around the heart area (going from the left chest all the way to the upper left back) and the left side of my neck. the pains in the areas around my heart are like pinches, sharp pains in ceratin spots that are only there for one second but sometimes it was also like a pain that would be there for a few seconds on a larger area one my left pectoral.
My left arm was feeling weak and numb, but i could still feel my fingers and i would also feel like needle pricks on the opposite side of the elbow, on the inner side of my bicep, on my forearm and on the root of my ring finger.
Whenever i got pains in my left neck, it was also like a ***** but lasted for 3-4 seconds and was way more intense.
i've been literally worried sick that i may have heart problems/ a heart attack. i went to the hospital at midnight 3 days ago because i couldn't sleep because i was so worried. the doctor just checked for a problem in my ribs or something and didn't check my heart and sent me home with deflammatory pills for muscle pain.
When i was on my way to school yesterday i started feeling pain in my left arm and started freaking out (o yeah i've had anxiety attacks every one of these days, nausea, feeling down, freaking out, sweating, thinking im dying) and decided to go to the doctor. the doctor used the stetoscope around my heart and then had me get some xrays of the chest. when they came back he just said that it was probably a pulled muscle or something.(cont.)

[CCF HeartMD3]

jpmezart,
While all things are possible, heart attacks are extremely rare in patients of your age. Chest pain from a heart attack is classically a severe pain in the chest that radiates to both the jaw and/or left arm. It is diagnosed with both an ECG and blood tests that look for heart damage. I would advise you to find a good primary care physician who can talk about symptoms and devise a treatment plan tailored to you.

[jpmezart]

(cont.)this morning when i was coming down the stairs i felt some pressure in the middle of my chest ,and since i read that it was a symptom of heart attack i had the worst anxiety attack yet. i started shaking and almost crying and had to breath slowly through my nose to calm me down. it lasted for like half an hour. now what i've been feeling all day is a pain that goes from my upper left back all the way to my elbow. it doesn't hurt much it's more a discomfort: it feels  like when you hit your funny bone but not as painful (like current running through my arm) and sometimes pain in my left middle or ring finger and the pricks around my heart more often than before .this leads me to believe that i may have a pinched nerve or something and the pains are just a reaction, but the doctor didn't tell me anything about that.I can't stop worrying about having a heart attack. Is it possible that it could be heart problems?