Recently, I got a new rat called Leah. Today I noticed that she was stumbling about and falling over in her cage. Her head was tilted to one side and she was walking in circles. I got her out of the cage, and she rolls to one side on my hand, like she can't stand straight. I put her on my bed and she just walks in circles with her head tilted. She also keeps rolling over, always to her left side. Please help, she looks like she's in a lot of distress. I've put her in a single storey cage, and I'm going to ring our vet tomorrow morning. Anybody got any ideas??