It is possible for a woman to lactate while she is not pregnant. This can be caused by some medications like thioridazine or metoclopramide that causes a rise in prolactin, the hormone responsible for milk production. Consult a medical doctor for more information.
in addition to geekout, you can also lactate from extreme change in diet, abnormal amounts of emotional or physical stress, switching birth controls or starting/ stopping it. also, which is overlooked, having a good bra is not only essential to back support & chest cramps, but if there is too much free movement going on it can cause lacating & other health risks.