First off there is no way you are a bad mommy!

I think that the way Kia is acting has something to do with the way she is feeling. Not necessarily depression but just not feeling up to par. When Jack had the diahrea and vomiting, the vet said that dogs get bugs like we do. Could be Kia just has one of those "I don't feel good" bugs with the symptoms only being listlissness, lack of appetite. Dazzi disappears into her crate when she is not feeling so well but it has never lasted more than a day or so. I would give her another day or two and see how she is doing. However a phone call to the vet doesn't cost anything and maybe they can relieve your mind about it being something more serious.