Write me a text to someone I work with asking them to cover my shift because I got sick. Use a polite tone. 
 Hi <insert name here>, I’m running a fever and my doctor recommended I find someone else to take my shift. Unfortunately it’s contagious and I’m worried that I’ll get everyone else sick if I go. Is there any chance you could step in for me? I’ll owe you one big time, but totally get it if this is too last minute. Let me know!