I don’t feel good, but I have to go to school/work, what do I do?

I thought I was just getting over a cold I had, but I feel achy, have chills, I think I might have a fever, my back and stomach were cramping a lot yesterday, and I’m exhausted. I already a day of class and work a week ago, and attendance policies say that your grade drops with absences because you lose your points for the day. And I don’t want to miss work again. What should I do?