This type of pain appears to be muscular.. it may be due to chronic muscle spasm in upper back and shoulder muscles..
Are you involved in any heavy physical activities or working in sitting posture for a long time daily. These may be some of the reasons for the pain..
Next Steps
I will suggest you to start with Hot fomentation, take analgesic with muscle relaxant, avoid heavy work, if you are doing sitting work, take intermittent breaks.. Physiotherapy can be started including Local US, SWD..