What Causes Deep Pain In Left Shoulder Blade?

Since November of 2014, I ve experience deep pain underneath my left shoulder blade. The pain becomes worse when I lay down and I cannot lay on that side of my body at night. I can play golf, swim, garden without too much discomfort. However, it tends to bother me more, when I m inactive. The pain radiates from underneath my shoulder blade to my neck. It doesn t hurt for me to raise my arms, cough, rotate my arm or move my shoulder. The only other symptom I have is that when I move my arm...there is a popping noise that seems to be coming from my shoulder close to my spine. It doesn t hurt when it pops...but it pops loudly. I cannot reach the pain..as it is underneath my shoulder blade. I have had deep tissue massages, saw a orthopedic surgeon....a) he took an x-ray which showed nothing...b) gave me a cortisone shot deep into the area under my shoulder blade (which provided no relieve at all), c) gave me anti-inflammatory drugs and steroids and there has been no in the pain. The pain is now disrupting my sleep and giving me headaches. I have an appt with my general physician next week to see if he could do an image of my shoulder. I m a 59 year old female..5 6 and weigh approximately 120 pounds. In great shape...although this is very debilitating . Thanks for your response.