Limp/not very responsive

When my daughter woke up this morning we found that she was limp when changing her diaper. She was also not very responsive so of course we instantly rushed her to be checked out. She’s staying overnight to be observed and they haven’t found anything wrong with X-ray/ct/bloodwork and they didn’t have the urine results back yet. After having some saline in her IV and a nap she seemed like herself but now she’s going back and forth between acting normal and lethargic. Has this happened to anyone else? If so what was diagnosed? If this hospital releases us without an answer we will be driving over an hour to the children’s hospital.