I Have An Discomforting Sensation Behind My Left Breast An

I have an discomforting sensation behind my left breast an my shoulder at the back. Iv had an ech and its ok. Iv had this since yesterday evening at 5.45 and i went to the doctor who sent me to the hospital. The wait was 6 hours so i figured it wud be ok
I still have it this morning.
It there all the time and it doesent change wen i breath.
Im a diabetic type 2 on insulin.
Annette kelly