What Causes Pain In Breast After Lump Removal?

I ve been having a small pain in my left breast since 11/2014. Sometimes when I m at work or feeling stress it s a little more painful. In 2010 I had a non cancerous lump removed from my right breast. I physically discovered this lump. I am a 45 year old man. What could this be as I don t feel any lumps. But I feel the pain in one area of my left breast.