I myself was down for 3 1/2 days with the bug and have been left with a nasty cold.
When should I start to worry dd(9) temperature is up a down, sleeping most of the time (most unlike her) had each ache (getting better) and a cough again getting better . Thought yesterday things were looking up dd was off the sofa playing cards. Only slept a few hours in the day. Then by about 6 she was asleep again and within a hour she was feverish again.
Slept from 7-7 last night. Had a tiny breakfast (has been eating nothing, again so unlike her), by 9 she was asleep again and still is now.