Hi, Welcome to JustAnswer. I am a licensed veterinarian and I'm here to help you. It does sound like Spooky is ill with something, not feeling well and therefore not wanting to eat. Since she just queened (gave birth) it is possible that there is a retained kitten or placental tissue in her that is infected, but really any illness could cause her lack of appetite. Does she have any other symptoms other than not eating? Are the two remaining kittens nursing well and are they satisfied?
You could try offering her some baby food meat (ones made without garlic or onions). Warming this up will bring out the fragrance and make her more likely to eat.
Ultimately, if she is not eating within 12 hours, she should see your vet there. . .not only is not eating dangerous for her, but for your 2 little kittens.
Please respond with any further information or questions that you have. Thanks!