Pain in the left side of chest. neck and shoulder. feel it when i sleep on the left side. smoke and over weight?

Maybe nothing but...: Shelley, The fact that it is positional (and not worse with exertion) would indicate more of a muscular condition. That being said, you have two major risk factors for cardiac disease (you smoke and are overweight). If you have high blood pressure, diabetes, or a family history, that would add to your risk. You should have an EKG and stress test done by your doctor to be sure. Hope this helps!

Mystery: It's too much of a mystery to guess the cause - It's likely to be something simple like a muscle strain, but. Why not take this opportunity to start moving toward managing the weight and smoking? Once you do those things, pains will still be a bit of a worry - but not nearly as scary. You can find good help for both goals and doctors will treat you much nicer. Think about it. Best!