Hi, Both Of My Friend's Breast Have A Bloody Nipple

Hi, both of my friend's breast have a bloody nipple discharge. . Her prolactin is normal. . the blood sample was negative of cancer cells. . She has no lump. . and she's not losing weight. . Her OB Gyne scheduled her for Breast Ultrasound. . but she also wants second opinion from other doctors. . From what kind of doctor should she seek help? Thank you so much^^