You are a teacher? Yall aren't slaves. Parents shouldn't expect you to never get sick or need personal time off. They should be able to expect for you to have a good aide that's in the loop and can cover though.
I am in my 24th year of teaching. As I mentioned I have been blessed with good health and I suspect that my immune system is protecting me from just about every illness the kids have come in contact with. My first few year teaching were the worse for getting illnesses. One year I used 15 days when I had a bout with mono.
Another year I used all my sick day to recover from back surgery (that was 45 days)
In high school and middle school, only the special ed teachers have aides, and they are becoming increasingly infrequent in the lower grades as well.
None of us teachers here have classroom aides.