Was diagnosed with torticolis, have constant severe pain in neck/shoulder area and small of the back area. numbness on left side on back. causes?

Muscle spasm?: Muscle spasm or rigidity can be painful. See a movement disorder specialist. You may need Botox injections.

Pinched nerve: A pinched nerve in the neck also known as a cervical radiculopathy can present with significant neck pain that radiates to the trapezius muscle, the area next to your shoulder blade on your back and sometimes down the arm with associated numbness.