I have had a pain for quite some time in my shoulder left arm and under my left breast. shoukd i worry? what coukd it be?

See doctor: Its important to establish a diagnosis. Shoulder/arm/breast pain could be from 1) referred sources including: neck, abdomen, and heart. 2) shoulder sources include: arthritis, labral tears, instability, tendinitis, rotator cuff tears, bursitis, painful bony spurs etc. Therefore proper diagnosis is essential to stopping the pain. See an orthopedic surgeon.

Should check it out: Heart trouble is relatively rare at 27, and you are not reporting any lung symptoms such as sob/coughing etc... So, what bothering in the shoulder area is likely musculoskeletal. It is not dangerous or urgent, but seemingly a concern/bothersome to you so should get it checked out. I suspect some bicep tendinitis, ac tendinitis, or bursitis of shoulder. Motrin/aleve may help. See doc. Good luck.

Yes if it bothers u: Whatever the cause, if it bothers you enough, you need to consult a doctor about it. Since you have diabetes, coronary disease is always a consideration even though it is unusual at your age. There are too many potential answers and thus you will need to see a doctor to help you find out what the cause may be.

Shoulder arm pain: There are many possibilities. It may be some injury or past trauma to your arm and chest. You will need to have a doctor examine you to determine the cause.