thank you so very much for the answer!!!!
Hello and hope you are doing well.
It's unlikely to be cardiac, as it changes with posture. Sometimes repetitive injuries or strain can also produce these symptoms. Working conditions or postures can cause a muscular imbalance from front to back, or side to side. That's why when you change postures or position the pain disappears. For this adjusting your postures like moving the mouse on your computer closer to you, so that you don't have to lift your arm forward or out makes a big difference in the pain pattern or moving your seat position in your car to avoid leaning forward while driving, these measures can help alleviate pressure and pain under shoulder blades and pain in the shoulder and neck.
The pain can also be due to orthopedic related causes like cervical rib, cervical spondylosis or disc prolapse. A simple x-ray will help and an orthopaedician can guide you.
Hope this helped and do keep us posted.