Chest pain on left side and then a deep cough??

Ive had this for months now and I've been to the doctor several times for this chest pain and the cough! I was told i had bronchitis infection and then I was told sinus infection...all the medicines haven't worked at all! Even when I'm doing an activity like dancing or running..the cough gets worser and its a deep cough...i can't get rid of it...anyone can tell me what to do or what they think it is??