Possibly Columnaris. First, I would move her to a clean, separate tank. On both tanks do a water change, vacuum the gravel, lower temp to around 75F if possible, increase aeration with an airstone and by lowering the water level, if it has a HOB filter, and treat with Maracyn and Maracyn II together for at least ten days. Don't know what effect the treatment would have on the babies, but that's what I'd do if I wanted to save the fish.
Otherwise, just get her away from your other fish ASAP before it spreads and kills them all, and still do everything mentioned for maintenance to the main tank and keep the temp down, O2 up.