Welcome at HCM.
I have read your question.It looks from your details that most probably you may be having rhomboid muscle strain
.The rhomboids is one of the muscles which attaches to inner boarder of scapula
.This can occur due to over use of muscles or working with out warm up.
At present you should do following to have relief in this-
-Do warm fomentation over that area.
-Avoid excessive use of your shoulder .
-Avoid abnormal posture on desk especially when you are using computer.
-Take the help of a physical therapist.
Hope this all will help you.
With best wishes.