I spent probably a couple of years wondering why I was constantly sick with flu symptoms, I thought I was catching ever virus that went around. finally I realized it was depression making me feel physically like I was hit by a truck. In fact now I know depression is coming back by some of those physical symptoms. I still get constant headaches but like Tel32693 I think stress is a big factor, and anxiety. I notice my neck and back muscles are constantly tight and that can't help the situation.