What Causes Pain In The Upper Left Back?

Hello. Two days ago I started having a serious pain in my upper left back. I thought it is a trapped nerve. Now I have also a severe shooting paing in my left chest it is difficult to breath deeply and when I cough it is too much to take. I suffer from regular sharp pain in my chest which comes avery 1 minute or so. It hurts so much. The back pain still continues. Could you please advise what it is and what to do. Thank you.