I have a 2000 chevy caviler. I filled the antifreeze on the 5th, and the 11th it was empty. I filled it again and on the 13th it was almost empty again. My oil is clean. My exuast is not blowing smoke. No signs of a leak. No smell.. What could it be?

You obviously have a leak somewhere. A good radiator shop will have a dye that can be added and will show a leak under ultraviolet light. Probably worth it to have that done first.
How does the car run? It could be a head gasket leaking. Not the first in those motors.

Car runs great. I will be sure to have that done.. Thanks

That much coolant loss should be quite visible.
The leak could be hitting the exhaust and burning off before you see any puddling on the ground or on the car.
However, the dye test should show a small leak that isn't readily visible without the dye.

You could put some large pieces of cardboard under the car and run the engine for awhile to see where it gets wet.
Check the area near your water pump. It might be going out. You wouldn't see anything burning off, smoking, or smell anything because the coolant would be running straight down. You have to check the pump when your car is running .