My 3 yo was sick 7 days ago in the middle of the night and a couple of times the next morning. Ever since he has feel fine during the day and has been eating and drinking. But for 5 nights out of the last 7 he has been sick once, gone back to sleep and is ok again the next day. My daughter is experiencing similar but she has only been ill the last 3 nights. Is it normal for a sickness bug to go on this long and for the child to only be sick at night?