I have sharp pain below my left shoulder. x-ray, ct scan, and ekg show nothing but small cysts on liver and kidneys. where could pain radiate from?

Systematic workup: Pain under left shoulder could come from several causes. Your doctor should take a detailed history and physical exam, then order appropriate tests.

Muscle injury: Assuming that all of your testing such as ct scans and mris are normal you may have simple muscle spasm. I would advise of massage therapy or physical therapy to see if they can relieve your symptoms.