my kizmoe was about 3-4 and i had got one of thoses furbys and sat it in livingroom, within the next two days he was moping around not waging his tail , didnt have any energy and eating less, i took him to dr , he checked out good , so dr ask if anything changed in my house i told him no, he ask if i had broung anything new in the house ,than i remember the talking furby. i went home put it in a closet and he was well, he though it was real and taking his place. so have you gotton anything new that he/she might not like?
Play with it, cuddle it, walk it, give it treats, and maybe give us all more info so we can help :)