I’ve never tried ritual magic, but when I was studying jiu-jutsu, my teacher told us you should probably knock off for the day if you have a fever. The dividing line for practice without fever was the neck—if your symptoms were in the neck or above—sniffles, sore throat—you could safely train. Below the neck—coughing, upset stomach—take the day off and get better. (Training with sniffles meant stay home and train by yourself so you didn’t infect the whole class.)
Re: sick
Get well soon!
—Princess Cutekitten