How do you know John is really sick?

He gets himself ready for bed and tells you he is ready! He has been pretty miserable today with a runny nose and cough and even took his nap. Tonight I ran out to wal-mart after Ruthanne went to bed figuring I would be back in time to put John to bed, but when I came home he was getting his teeth brushed and was rushing Luke to let him go to bed. Luke even tried to get him to rest out in the living room, but John said he wanted to rest in his bed! Poor boy, he must be really sick, because he will fight sleep like crazy normally!