Rats do not get colds and when they are ill it is very serious.
Rats get sick and die quickly.
What color should her ears be?
It is possible that she is not getting enough oxygen if her ears are too pale ... are her toes turning bluish?
What is her breathing like?
She may be dehydrated ... make sure she is getting enough fluids like pedilite or the homemade rehydration fluid (see
viewtopic.php?f=26&t=11058 )
Ensure or pedisure is good to keep her energy up, also baby cereal mixed up with ensure or soy infant formula. People say their rats like vanilla flavor best.
You can give her one drop of fluid in the side of her mouth at a time by needless syringe. One drop at a time in the side of the mouth is so the fluid doesn't run down her throat and into her lungs.
Can you give us more info.
At this point in time, all I can suggest is to get her in to see a vet as soon as possible
and like jorats said, keep her warm and hydrated.