My daughter is 2 1/2 and her temp has been up near 39c now its down to 35c. this has never happened before what should i do?

Fever: Fever above 38.5 is usually a sign of infection of some sort. You have not given me much information but i would go see your physician to determine the reason for the fever now.

Possible emergency: Normal temperature can vary between 36.5 to 37.5 Celcius through the day but both high and low temperatures may be a sign of infection or other serious problems. Take your child to see a doctor immediately.