They thought it was a gall bladder issue, and have done a few tests on her, but we're still waiting on the results. I was there with her until about 10:30 tonight, when it became clear that it would be awhile -- probably tomorrow -- until we really know what's up.
It's probably not too serious, but right now I'm missing her and want her home healthy... as soon as possible. She was supposed to go out tomorrow, but I think we need some "stay at home and cuddle" time -- ideally for the entire weekend.
***Update - Just heard a bit more. Sounds like Kirsten has some kind of abdominal infection. They're admitting her to the hospital for the night (and possibly for tomorrow night as well) and giving her antibiotics to fight it off. Still not entirely sure what caused it, but hopefully their course-of-treatment will help get her back to normal soon.***