Nipple discharge

About a year ago I was suffering from really bad cramps and tender breasts. I was massaging round the side of my breasts towards my arm pits with my hot water bottle on me to help with the cramping. I noticed after a while that my nipple had a small drop of liquid on it. I called the doctor and they did a blood test to check for high prolactin levels and it came back all clear however during any sexual activity they sometimes have a small amount of discharge. The doctors say this is normal if they are touched however it is a clear colour and not white and I just wanted to know if anyone also experices this and have you been told it is normal too?