Horrible pain in my upper left lung?

i started smoking when i was 12 im just about to turn 18 i dont know if the pain im feeling is realy my upper left lung or not but i think it is. also i dont know if its from smoking. The pain is so sharp i dont know wat to do its always there i just knoticed yesterday. If i stay still and dont breathe to hard i cant even tell its realy there but if i move a certain way or breathe heavily i know. i was a pack a day smoker since my freshmen year i normally chaned smoked. ive been around smoke all my life as far back as i could remember some1 lived with smoked. i dont have money to go to the dr's and find out its nothing im down to smoking only 1 or 2 cigs per day also ide say half the time i smoked were menthols . wat should i do? do i realy need to go to the hospital?