I think my chinchilla marlo used to chew the cords in my room... well I KNOW he did. But about 4 years ago, when he was out in my room, now and then he would just kinda go limp, and sometimes twitch, and just lay there in my arms, I took him to the vet every time it happened, but she coudnt find anything.
Then when I changed my room, I made sure ALL the wires were 1/2 way up my wall, covered with this plastic wire covering so he couldnt get to it at all. And all the sudden, he stopped doing that. So I think it was when he found a wire and chewed on it that he would go all limp.
-But even though you think you have all the wires covered, they always find a way!! smart little critters =)