Write a question about the following article.

I woke up with body and stomach cramps and a mild temperature ... oh oh . So I basically ate nothing and spent the day in bed . It proved the right strategy because 24 hours later I was much improved ! In retrospect I had the virus for a couple of days and the muscle pains were part of what made the bed uncomfortable .

Question:
Why is the narrator potentially sore ?
Options are:
I. They are suffering from a bad day ..
II. They are suffering from a sports injury ..
III. None of the above choices ..
IV. They are suffering from an arm injury ..