I had my second mammogram (baseline was 1 yr and 5 mos prior was "normal") and it showed "a 6mm new mass with well defined margins in the left breast at7 o'clock. I had a diognistic mammo about 7 days later and it showed "an 8 X 6 mm, equal-density, oval mass with lobulated margins in the lower inner quadrant of the posterior amedial left breast at 9 o'clock." I'm scheduled for an ultrasound on 6/6. I feel like 6/6 is an eternity away and I'm worried. What could this be?