Causes of leaking colostrum when not pregnant?

Nipple discharge: Nipple discharge in a woman who's not pregnant or breast-feeding isn't necessarily abnormal, but should be evaluated by a doctor. A nipple discharge may look milky, or it may be yellow, green, brown or bloody. Nonmilk discharge comes out of your breasts through the same nipple openings that carry milk. The consistency of nipple discharge varies from thick and sticky to thin and watery.