help!

Question
My two and a half year half year old female guinea pig Arianna was lying on her side, in her cage, kicking like crazy. At first i thought she was just playing (my dog sometimes does that in snow) but then i saw that she couldn't get up, so I gently lifted her up and she just fell over again. I tried to feed her some lettuce, but she didn't eat it, (And she's never not eaten lettuce before).

Answer
she could have a condition called head tilt, this is where mites have got quite far down her ear. not to scare you but it is very serious. alternatively it could be a plathera of other things but either way I would get her to the vets as soon as possible.

best of luck and I hope your guinea pig gets better