You really need a scale. Get a baseline weight ASAP, then one really should tube if they are still loosing weight. Knowing how much she weighs is so important because it allows you to calculate if she's getting enough water. Ideally she should consume no less than 25 ml per pound per day, but...
Tube feed. Start with fluids at 9-15 ml per pound, wait 60-90 minutes and repeat if crop is clear or mostly clear, then give fluids one more time in 2-4 hours. Once fluids have been given, tube Kaytee baby bird food at 9-15 ml per pound 2-4 times a day.
You can get Kaytee at Petsmart or Petco...