I am 21 years old and I just had my first son february 15, 2009 but this is my second pregnancy. I had breast feed him for two weeks after he was born. Well yesterday I was checking my breast and there is an lump on the right breast by my nipple more on the left side. It was not there the day before or any other day and it is a little tender and it feels bigger than a marble. I wanted to know your opinion on what it could be?