I have a three year old dear chihuahua and she's usually really happy and ready to go in the morning. But, today I woke up and found her at the foot of my bed laying down not wanting to get up with cold ears.

First things first, if you have a digital thermometer take her rectal temperature.
101-102 is normal. If she is cold you will need to warm her up. A towel from the clothes dryer will work nicely.
If she hasn't eaten recently her blood sugar may be low, you can rub some Karo syrup or even pancake syrup on her gums, for a little boost of sugar.
As soon as you check these two things get her into the vet ASAP and get her checked out.
The two things I mentioned will only buy you a little time to get her to the vet, they are in no way a "fix" for any problem that may be causing this change in her.