There are times when we fall ill. It’s hard to raise a child without recurrent bouts of ear infections and colds, and as adults we are susceptible to a variety of germs. Think of all the possible ills: bladder infections, pneumonia, cold sores, viruses.
If we are lucky there are medical treatments to help us recover. Children often go through antibiotics like adults go through booze. We suck on throat lozenges, spray sore throats, guzzle cough syrups and rub on any variety of ointments to ease sore muscles.
Your characters are exposed to disease as well. You have to decide what types and for how long they suffer. What medications or courses of treatment they follow. How they handle being ill. Does he tough it out, refusing to let fevers and chills slow him down or does he fall into bed at the slightest indication of illness and stay there, being miserable, until it passes?
These are things that you must decide.
Your task is to write a scene in which at least one of your characters gets sick. Before you begin, make a list of possible ailments. Go online and do some research, looking for symptoms and cures.
Once your list is established, narrow it down to those things that you feel most comfortable writing about. You might stick to those things that you have personally experienced.
Then write. Have your character fall ill. Based on her personality, have her react in a logical way. Send her to the doctor or hospital. Put her in bed. Give her reactions to the course of treatment.
Who will tend him, providing food, clean clothes and nurturing?
Who holds her hand and places cool clothes on her brow?
These are all the things you must consider as you write.
Now, make your character sick!
Have fun with this one.