feeling very sick, need some guidance

Hello, just as my title says, im feeling ill. I am a new employee so Im still on probation and can't use my sick time. I was wondering if calling in for the next 3 days is okay? I have a fever of 39 and I cant get out of bed. I feel awful for even thinking of calling in but i really dont think i can work for the next 3 days. Any advice?