You are having issue with breast milk still secreting even after having stop feeding by christmas, ( 7 months have passed) and you physician asked you to have prolactin
level checked and you want to know what is the prolactin and why do we advice that test.
Prolactin is a hormone - (pro=before and lactin= milk ) so literally it means a hormone what is secreted from the brain to start the milk production. So as long as the prolactin remains high in the blood your breast will keep secretion the milk.
so if we know if the level is high or not that will help us to know what to do and which medicine will help.
The medicine name "bromocriptine" will help to resolve your issue if the level of prolactin in blood is high.
Hope it helps.