Is nipple discharge from one breast normal? i've taken pregnancy test and they have came back negative

Nipple discharge: Nipple discharge is sometimes a result of increased prolactin. A blood test will reveal elevated prolactin and should be performed to rule out pituitary adenoma. Not rarely, however patients that continue to check the breast for discharge will inadvertently stimulate the release of prolactin. Simply not touching the breasts for 3 months will usually stop the discharge.