I fully agree that you should stress dose for a whole day.  Our endo.  always told us that we could stress dose up to 3 days without any harmfull side effects.  If child is sicker longer than that they should be in the hospital.  We have never had to do it for three days, but we have done it for 2 (during times of the flu and bad colds and fever).  My daughter is now 20 and no harm has ever been done by over medicating.