We have a nearly 2 year old blonde guinea pig named "Nugget". Nugget is a sweet, happy little lady. Last week I got her a new habitat, much bigger and fancier than her original. Almost immediately, I noticed she basically just hid under the shelf like thing. After a few days, I removed the structure so it's just a big open cage, much like her original one, only bigger. She is still out of sorts. She just stays in the corner, looking really sad! She isn't eating or drinking much either. Any ideas or suggestions?