The fix: The best way to combat the common nursing ailment of thrush—a yeast infection of the lining of your baby's mouth or her tongue that spreads to your nipples—is to know the signs. "I kept thinking that the white spots on the inside of my baby's mouth were just milk," says Wilhelm. "But it turned out to be a yeast infection, and by the time I realized it, my nipples were infected, too." Another indicator of thrush, besides those telltale spots: a burning sensation when you nurse. While babies' symptoms usually clear up within a couple of weeks, your doctor might treat you with a prescription topical cream.