Chronic ache in left shoulder blade now causing shooting pains into left chest/breast. what causes this and how do i heal it?pcp says not cardiac.

Anatomy of referred: pain. The tricky thing with pain is that it's chameleon-like due to the architecture of our nervous system. Is this worse when you lie down? (Kehr's Sign) Did it happen all of a sudden in the absence of a shoulder injury? Have you suffered abdominal trauma? Last mammogram? Because the phrenic, supraclavicular & intercostal nerves have the same cervical nerve root origins, the body gets confused.