My 9 month old daughter is having cold sweat and isn't eating like her normal self.

Early signs: This is probably just early signs of an approaching illness. I would make sure fluids are available and keep track of other signs that develop. Most at that age will become ill over half a day or less and the other symptoms may give you a better idea of the cause. Many viruses start this way.As long as she is wetting diapers every 6 hours or better, it is fine just to monitor at home.

???viral infection: she could be getting a viral infection.give her fluids and watch her temperature

See the doctor.: She may be having the start of an illness that needs further evaluation by a medical provider. A cold sweat may be a sign of a fever so please check her temperature and you can give Tylenol (acetaminophen) and apply a cold compress on the forehead and neck.