Why i have a mild pain in the left side of my neck and its persisting for a week till now is that from muscles or what should i seek medical help ?

Nerve impingement: can be caused by being sandwiched between two spinal bones, pressed by a bulging. It can cause muscle spasm and back pain. Prevention treatment is always recommended. This condition must be professionally managed. See interventional pain management specialist for definitive diagnosis and management. It is the same as a pinched nerve.