Frankie :/

Question
Hey, Im Anna im 13. I used to have identical twin boars, until the weaker one died because his teeth overgrew, it was heartbreaking. This was in 2009, and my other guinea pig frankie has lived 2 more years on his own happily and heathily. he was 4 in june 2011. A couple of days ago i went to give him his breakfast before school and he was lying there, I stroked him and he moved. Today i went in around 11 and he was sitting there in the hay. I gave him his food and stroked him and instead of running down stairs straight away he just sat there. I went back an hour later and he had eaten some food but was still in the same position. I put him in his run and he sat there still. I brought him into my room and put made him a little house out of pillows like I sometimes do, but he just stayed there instead of running into it for cover. i tried picking him up but he let me. Now hes lying on my bed in a blanket. Im really worried about him. :'(

Answer
is it that his back or front legs are not moving? is his underside clean also, and is there a noticible difference in the size o his testicles since you initially got him? I would get him to a vet as soon as you can, in the mean time make sure he has a dish of water within drinking distance where he is lying.