My 3 yo son had congestion and fever. the fever only lasted a few hours. now he has cough. why was fever so short? does cough mean it's almost over?

Upper respiratory: infections are usually viral, of short duration and self limiting., For the first several days and up to 1 week - over the counter analgesics and fever reducing medications like Children's Motrin or Tylenol (acetaminophen) should be sufficient to control any symptoms. If these persist however after a week then it is reasonable to see your local family doctor or pediatrician for guidance.

See Your Doctor Now: Fever is triggered by immune response to infection. It's features (duration, intensity, etc) vary based on cause & individual immune responses. Viral upper respiratory infections are common at this age & can cause cough; usual course is 2 wks. However complications (pneumonia, etc) can occur; children do not complain; cues to worsening are missed. See doctor now for correct diagnosis & treatment.