Have been having upper abdominal pain that has radiated to left shoulder/neck region. it only hurts when i breathe in deeply, cough, or sneeze.

Abdominal pain: The pain described has the characteristics of pleural origin, it could be from the bottom of the lung covering irritated what is called pleuracy. It could be from the irritation of the diaphragm or heart lining tissue and muscles. Having said all these based on the history, you need physical to narrow down the diagnosis. Get it checked out if problem persist.