Green discharge from right breast

For the past year or so I have had greenish yellow discharge from my right breast when I squeeze. Sometimes I also have some milk discharge as well but not very often. I talked to my doctor and he took a sample of the discharge and ran tests on it. Everything came back normal, prolactin, thyroid, white and red cell count,...everything. He ordered an ultrasound of my breast and that also came back good. So I'm at a loss as to what to do. Should I seek a second opinion? Should I just ignore it? It doesn't hurt or bother me at all, all that's there is the discharge.