I have had pretty bad pain in my right shoulder blade for about 6 months now. It is not constant and it appears when i sit down on my sofa or computer chair for more than 20 minutes. The pain is so bad that i have to keep my arm still and pray it goes away quickly. It usually lasts for 2-20 minutes and I just don't know what it could be! I have not done any rigorous exercise in a while and I have not lifted any heavy weights so i don't think ive strained it or pulled a muscle there. Please tell me what it could be and how to get rid of it thanks.