What Causes Stiffness And Pain In The Back Of Shoulders?

Hi Sir! From the last near about 30 days, I have pain in my right shoulder back side, just near the back bone. before it was stiffness and I was uncomfort to turn my neck. my friend give massage my back and apply an extra force after that my pain become worst and now there is more stiffness in my back side of shoulder. I shall be obliged for your advice and prescription. thanks.