Last night, as we were getting ready to go to bed, Nya (who is ordinarily a VERY quiet cat, I've only ever heard her "mew" softly and purr) let out an ungodly yeowl unlike anything I'd ever heard. Buddy is a yeowler when he's bored, this was different. It was gutteral and pained and to be honest sounded like death. She did it twice in succession. The first time I jumped and said "what the he!! is that?!" and the second time I realized it was Nya. When I called out to her she stopped but seemed confused and was really uncoordinated, but that subsided to her normal level of stumbling after a few minutes. Any ideas on what this might have been? She threw up a few times last night but that's not unusual for her these days. Her belly has been tender for months but the vet has basically told us not to worry about it. I went to bed last night actually afraid of hearing her make that noise again. It was the most horrible thing I've ever heard from a cat.