I Have Been Having This Pain Under My Left Breast

I have been having this pain under my left breast and it soemtimes rediate to thrbleft side of m y back. I can sometimes feel it above the left breast close to the arm pit. Sometimes the area under my breast I'd very tender. I did an ekg and an echo about 2 years ago and it had suggested that I had a mild pericardium effusion. My doctor said it wasn't anything tto worry about.