My recommendation would be to buy some MS-222 (aka Tricaine or Aquacalm), available at many specialist aquarium stores. If she starts to go downhill further, mix up 1 gram per L of water and add 1.5 grams of baking soda (to counter the acidity of MS-222). That should gently put her to sleep. Clove oil works too, but I've never used it myself.