Sharp back pain around/under left shoulder, going through my chest when taking deep breaths. worrisome?

Seek help: This could be musculoskeletal or it may be cardiac in nature for example. See you internist and than follow up with your orthopaedic surgeon if symptoms persist.

Possibly: The symptoms don't sound like something that is life or limb threatening. However, I am sure you are in a lot of pain. The cause may be a herniated disc, something that doctors don't often think of when evaluating someone with back and chest pain. If you do seek medical attention, ask you doctor if he/she thinks an spinal MRI would be helpful.