One of my child Sims suddenly took a Sick Day from school. I tried to have him take medicine, but there's no option for it and his parents can't give it to him either. Can Child Sims not take the Medi...
Do you have “Change Sim Info... > Remove Moodlets” in your shift-click menu? If it’s there, you can use that to remove the hidden illness moodlet. It’s the one with the name of the illness (e.g., Llama Flu).