Hello. I'm 42 years old. My mammogram the past 2 years have come back normal. I have my mammo coming up soon. But last night, I discovered a small round lump near my left breast, right outside the edge of the breast on the rib bone below the armpit area. So it is basically underneath the side bra strap. My Dr did a manual check of my breasts on 12/11/13 during my pap smear, and she did not feel any lumps. But last night I discovered this small round lump. I started my period today. Do you think the lump is most likely benign, related to the period, etc?