Sick Days and Guilt

I wake up this morning with my throat all th way up to my left ear swollen. I can barely swallow and even low level television noise hurt my ears. Why then do I feel so guilty for taking the day off of work to recover? I know that if I went into school, I'd be miserable and possibly contagious. However, as I let my school know this morning that I wouldn't be there, I felt this overwhelming sense of guilt.
It's partially for my students - no one learns as well from a sub because the sub doesn't know the class or what is going on. There are some fabulous subs out there (as well as some horrid ones), but no one can overcome in that in one day.
The second thing is that I feel it reflects on me poorly when I'm sick. In other jobs, people take sick days more frequently because they lack good vacation time. In the teaching profession, we have so many days off that I feel like we should be there everyday. There's only two more weeks until Holiday break, I should be able to hold out until then.
Alas, I stayed home today and slept for an additional four hours. When I woke up, the swelling in my throat had gone down and I felt much, much better. So, I know I made the right decision for me, and the guilt is just something I'm going to have to deal with.