[Quiet Man Cometh]

I've swallowed a mouthful of *really* sour milk before, and was fine, apart from running my tongue under the tap for a bit. (Someone left the fridge door open while we were in Florida during a heat wave. I was in a hurry and didn't check). It's really a matter of it just tasting bad. If it doesn't taste good, toss it.

Poor Kitty. I had to do a similar thing with my dog when he was nearing the end. He was just too weak and it was hard for him to stand up. The vet thinks it was probably stomach cancer (I didn't bother to get the tests done because the dog was 13 and likely would not have survived the test anyway). He deteriorated fast, over maybe a couple weeks.