I m 16, healthy weight, I exercise regularly (swim), and the only time I ve ever really been sick is a urinary tract infection. But I feel like I have a heavy weight on my chest where my heart is. I can t take deep breaths and I feel a dull throbbing pains all over (especially joints) but concentrated in the upper part of my heart. My upper back (like behind my heart) hurts and also my left side by the ribs. I feel really anxious, and it s been like this for almost three days now. I can t calm down, and even if i m smiling and happy it still hurts. I had to leave school friday because in class I had short breaths like I was struggling to breath. I can do normal activities just fine only difference is the dull throbbing pain. Is this serious? Do I need to go to a doctor? can you diagnose me?