Oh, dear, I'm so sorry.... if there's anything I can do, please let me know.

It does sound like Sweetie had a problem with low blood sugar - strokes are very rare in cats, and the fact that she got better with karo syrup is a good sign. Even if it was several hours from her last shot, that's still possible. So she should be fine, once she's regulated. As for Mischief, it sounds like you've done everything you can, and she's had a long and wonderful life. Please, if I can help in any way, tell me?