I always feel pain under my back shoulder blades, especially in winter. I don't know why . Maybe because i am sub-healthy. I 've never had any tests, and I think I lack of physical exercise, but I always fail to do that even though I swear to myself. ^_^
you should go to a cardiologist and get it checked out, I been reading alot on what people write on here and it seems that if you feel there is somthing wronge with you dig tell you find out what regardless of what some doctors might say, and some do find out.
I am trying to find out whats wrong with me myself, Im 24yrs old, chest pain under my left chest bone, some times under my back shoulder blades, I had an EKG, Chest X-Ray, Blood Chemistry Test, Stress Test all came out normal, but I will continue to look. Wish you the best.