How do i let me stay home from school, i'm actullay sick?

stay home from school.. I have a severly sore throat, a bad headache and a slight fever. I know for sure i have strep throat,well im pretty sure. and she is yelling at me and saying i have to go to school. because in the beginning of the year i was out alot because i have a weak immune system and i take a while to make up work. I even told her she can go and get my work.. and i would do it as homework and she still wouldn't budge