This sounds like a similar situation to mine, though my piggie hasnt been hurt...yet. My friends come over, they call it a rodent or rat, and when I leave the room I come in and something is always happening to them! They will pick up my hamster and dangle him, one of my friends even stuck a pair of scissors in my piggies cage near his face! I then got really mad at her and now she knows not to touch him when im not with her and I know she wont do it again, but i used to have a friend who would talk about hurting my hamster and killing it, but im not friends with her anymore, so its all good, and my friends I have now know not to touch them or I get mad, and I trust them, but that other girl...I didnt ever leave them alone. It really could have been them, because if that happened after my friends came over then I would think that too.