I have pain sometimes in my left breast, an under my breast, an around to my upper back an shoulder.what do you think that is?

Age makes answer: Check your bra tightness and weight gain. The shoulder and back pain all sounds musculoskeletal but depending on age we start asking more specific questions about the heart, shortness of breath, cheap pain, etc. I assume you are in your late 30's so this unlikely. Look for creases in your skin from the bra and make some adjustments there to start.