What Causes Muscle Pain In Neck And Chest?

I am a 44 year old man. I have shaky hands, I am feeling anxious. I have muscle pain in my neck and have noticed what feels like muscle pain around the lower part of my chest, around my diaphragm. These symptoms have been developing over the past month. I have experienced anxiety before. I also feel constantly tired, yet do not sleep overly well. I do smoke around 10 - 15 cigarettes per day and drink most days. I haven t had any major operations during my life. I have presented to my GP with stress before. My blood pressure, when last tested was normal .