Can stress & tension cause neck and shoulder pain especially if have injury n neck and shoulder? what if anything helps?

Yes it can: Absolutely, as stress builds people tend to have it manifest in increased muscle tension in the neck and trunk. This can easily translate to the trapezius area and therefore shoulders. Heat, cervical stretches, can be helpful. Meditation can be helpful as can exercise to relieve stress. Core workouts such as yoga increases flexibility and decrease stress as well.