What is wrong when you have shoulder pain that feels like an electrical charge running down your arm?

Nerve problem: Sounds like you have a pinched or compressed nerve. See an orthopedist or neurologist. Often times the longer youy wait to be treated, the worse the condition can get.

Pinched nerve: Your problem sounds like it could be a pinched nerve. But it the pain radiates down the left arm, a heart condition could be involved. Depending on the severity and longevity, see a doctor asap.