I tried to PM you but couldn't.

I am in education, too. It's hard because you sort of have to know ahead of time whether you will be out (at least where I work) in order to leave plans. Sometimes I miss my old job where I could just decide not to go or to leave early when I was having a bad day. I have amassed tons of leave that I never take because it's such a hassle. Every year I promise myself that if I am not in bed by X time, then I will call in sick the next morning....but very rarely do I actually do it.

It's much easier when I am physically ill, like when I am throwing up or have laryngitis. I think we need to give ourselves a break!