Prior to being diagnosed with asthma, I had pain emanating from my back and a very sharp pain in my left shoulder on one occasion last June. I was also sweating and short of breath. It lasted for about 2-3 minutes. It was very intense while it lasted so I went to the nurse's office at work.
She sent me immediately to the ER.
There they thought I might be having a heart attack and I wound up in the intensive care unit. I had to stay there until I passed the treadmill test the next day. It turns out that my heart was OK.
I was wondering what could have caused this but, after seeing your post, maybe it was asthma.
However if I ever do experience this pain again I will still go to the ER because the symptoms for a heart attack do include this.
Tom