Should I be concerned about my chest pain?

I struggled with chest pain and difficulty breathing for as long as I can remember I'm 16 years old now and a female my mom has taking me to the er where I' got an EKG and was told i was fine and also gone to the doctor several times where my doctor only tells me that I have gad generalized anxiety disorder.. Well I think I'm about old enough to know when I'm having an anxiety attack witch it's Been a while since I had one now but for the past three days I've been getting really bad chest pain on my left said that seems to go to my back, it also causes my left arm and shoulder to hurt, I feel as if my chest is congested or something if that's possible like if there's something stopping me to breath corectly I'm not sure if I should be concerned or not since I've been told many times i was fine.? Please help thanks so much! I've also noticed it gets worse with exercise and running.