Hello , If its a spasm heat pack from 20 minutes twice in a day will help but yours is long lasting so would advice you to visit a physiotherapist who can assess you better and give you certain modalities to reduce pain as well as certain exercises. As per your profession of being an engineer it needs to sit in front of the computer too with bad posture and long durning odd sitting too can cause pain. You may learn correct ergonmics from the physio the distance of laptop to be kept ; the height etc. Would advise long back support chair so even your cervical spine is supported  . Do frequent streches and neck movements.