[听力原文]6-7
M: Good morning, Miss Liu. This is James Smith.
W: Good morning, Mr. Smith.
M: Johnson asked me to call you up and tell you he’s sorry he can’t go to the art exhibition this afternoon. He doesn’t feel up to it.
W: That’s too bad. What’s the matter
M: Nothing serious. Just a headache and a slight temperature, but he thought he’d better stay in bed.
W: Tell him to take good care of himself and I hope he’ll be feeling better soon.
M: Thank you, I’ll do that.

What is the matter with Mr. Johnson（）