I have had pain on my right side right under my shoulder blade towards the back for about 2 months It is there most of the time and when I move just right it like grabs me right there and nearly takes my breath away, when I am lying down most of the time I dont feel it too much unless I move just right.
Did you have any injury or suddenly lifted some heavy weight? It can also happen with someone doing lots of exercises in gym or keeping a heavy bag on shoulders. Any way at present my suggestion to you is to start taking physiotherapy like local heat application, warm water shower over shoulder. You can also apply diclofenac ointment.  Chat Doctor.  If your pain improves after all these measures than fine otherwise get ultrasound of your shoulder to check is there is any nerve or tendon compression is there.