This seems fairly unlikely, but perhaps a pituitary microadenoma?  At any
rate, a serum prolactin measurement might give some info, if someone on the
list could say what the average serum prolactin would be in a mother of a
5-month-old singleton.  If her prolactin is as high as it would have been
just after delivery, it might shed some light on the situation.  (On the
other hand, the expense and trouble of pursuing this might not be
justified, if the situation self-corrects without adverse consequences.)

Arly Helm               [log in to unmask]
MS, Nutrition & Food Science, CLE, IBCLC