Can u advise getting pains in upper left arm for about 6 months the pain sometimes go down the arm?

Different causes. First of all, would like to know if any history of trauma prior to onset? If so, xray should be done to rule out a fracture. What bothers you the most:moving the neck or moving the shoulder? The problem could be coming from the neck, shoulder or a combination of both. Things to consider are Cervical disc bulge, cervical spondylosis,, radiculopathy, shoulder capsulitis, RTC tendinitis, etc.