My Lump

I have a hen-egg sized lump in my right arm pit. It appeared over night about a month ago. I've been squashed in a mammogram, ultra-sounded, and punched full of holes for a biopsy. Tomorrow I meet with the Dr. to hear test results. I have on family history of breast cancer, nursed 3 children, take vitamins, never smoked, drink very little, and exercise in a nonorganized way during the course of caring for 3 horses. I'm post menapausel, but over weight. I'm trying not to worry, but...