My doctor is testing me for a pituitary tumor because of breast discharge but nowhere near pregnant or recently pregnant, is this normal?

Common. Nipple discharge is relatively common in women. A pituitary tumor producing prolactin is one of the causes, although a rare one. Your prolactin levels also could be checked.
Yes. Sometimes an abnormality in your pituitary will lead to increased levels of prolactin. Increased prolactin can lead breast discharge.
Yes. The pituitary can produce a hormone called prolactin which can stimulate lactation.

Related Questions

Can I get preganant if I have a pituitary tumor anf my breast is producing milk from it?

Prolactinoma N preg. Small prolactinoma producing little prolactin may not affect your chance of pregnancy, but one that is producing much hormone will likely reduce your chance some what. Many women who are actively breastfeeding produce higher prolactin than nonlactating females, but they still get pregnant during this time. So if u r trying for it, good luck, if trouble, consult doc. Good luck.
Maybe. You should discuss this with your endocrinologist/ob/gyne before getting pregnant. There are risks to consider, especially that higher estrogen levels during pregnancy may cause further growth of prolactinoma which may affect vision, etc.