chest pain on my left side

Im 16 years old and ive been having there chest pains on my left side its my whole barest sometimes it hurts under my breast then sometimes on the left side of my left breast or the right side of my left breast or on top it hurts sometimes when i breath an sometimes it just keeps hurting an wont stop this started a year ago then it stopped now it started again its been 2 weeks an im not sure what it is should i go see a doc or will i be fine  i hope i made sense
thank you for your answer ^_^