Hi, Two Days Ago I Started To Get Its Like

Hi, two days ago I started to get its like a stabbing very bad pinching in my back more over to the left side near the shoulder blade in one spot its not there all the time comes and goes just a bad pain then its gone again for awhile then repeats. Last week the Dr. found a mass in my left breast I will be getting mammogram and ultrasound done in a few days could the pain in my back be the cause of the mass in my breast? or could it be heart related? I also have been itchy on the breast and under my left arm pit .Thank you