Dear zoe1981: Many women have some type of nipple discharge or fluid when their breasts are squeezed, and its normal. Squeezing the nipple sends message to the brain and the pituitary gland responds by increasing prolactin levels, which in turn produces discharge from the nipple. The discharge can come in a variety of colors - gray, green and brown as well as white. Some women are more prone to more discharge including women on; birth control pills, certain blood pressure medications or on major tranquilizers. These medications increase prolactin levels in the body. There is also certain life periods when a person is more likely to get discharge than others: there may be more discharge at puberty and at menopause than the years in-between.
The time to worry about nipple discharge is when it’s spontaneous (comes out by itself without squeezing), keeps on happening, and is only on one side. If it is clear and sticky, like an egg white, or bloody. If this is the case you would bring it to the attention of your doctor who could evaluate.
Regarding the lump, if this is new, it should probably be evaluated by your doctor. While it could be something as simple as a pimple, a new lump should generally be evaluated.