I am in my twenties, certainly not pregnant, and only 4 weeks ago I started getting a milky discharge coming from both breasts, usually only occuring when stimulated. I went to the doctor, took both an ultrasound and a blood test for prolactin levels and all these tests came back completely normal. The problem still persists; does anyone know what might be wrong? This has never happened before.

Just as a side note, I am taking Doxycycline, but it doesn't state in the information notice that it could cause such a thing.