Alexis - Is her body bloated or is she just floating?
In either case I would recommend putting it in a food safe container with lid (like an ice cream bucket) and putting it in the fridge. Use just enough water to cover the axolotl, this will help her regain her footing.
Keep extra water in the fridge to change its water with so you have water that is the same temperature. Keep its water clean and offer it food daily.
You may want to tape the light switch down in the fridge or cover the container with a towel so the light does not frighten the axolotl.
You should test your aquarium water for ammonia, nitrite, nitrate, and ph to make sure it is safe, and check the temperature.
What your axolotl is doing now by keeping her head out of the water and not being able to stay at the bottom of the tank is not normal behavior.
If you have not already found it you may want to visit caudatas sister site
http://www.axolotl.org/index.htm it is a must read for axolotl owners.
