Sounds like your puppy has parvo. Instead of seeking help here...you should be a the vet. Please let us know if your dog made it. :(
You need to take this puppy to a vet IMMEDIATELY! We cannot diagnose anything on a message board and if we could, the description you have given us of what is wrong with your puppy is so lacking in details there is nothing we could tell you anyway,
A nine week old chihuahua puppy who has not eaten or had anything to drink for two days is in grave danger of dying. It is almost a given that it is dehydrated already and probably has been since the end of the first day without anything to drink. If you let it go any longer without taking it to a vet chances are very good you are going to lose your puppy since it will start to have seizures from a combination of dehydration from not drinking and hypoglycemia from a blood sugar crash due to not eating. Very tiny puppies like that must eat several times a day to maintain their blood sugar. If their electrolytes become imbalanced from dehydration it causes a disruption in the heart's rhythm and you have a life threatening situation on your hands.
PLEASE, CALL THE VET NOW! Also, please post back and let us know how your puppy is!
Ghilly