Occasionally the stale smell can be a result of bedwetting the night before but this is unlikely in your daughter's case as you say she is washing properly. If your daughter is getting urine ...

How to Remove Musty Odors and Mildew Smells From the Basement You’ll Need: Dehumidifier or fans Baking soda White vinegar Activated charcoal or odor-absorbing packs Scrub brush or sponge Mold ...