My poor guinea pig

Question
I have no answers and I guess I am looking for one.  I have had piglet for a little over a year.  Thursday nite we cleaned our usual ritual of grooming, cleaning the cage and so on.  Piglet and cage mate Scooby ran around in there play pen while we cleaned the cage and replaced the bedding.  Piglet was fine playing away and so on. We finished everything and put them back. She was healthy and happy.  3 hours later my husband went to give them oranges and piglet was dead.  No warning or anything and I am trying to come to grips as to how a healthy looking cavy died just 3 hours after playing.  Any Ideas and advice would be appreciated.  I have her playmate still and she is kinda lonely for her mate.  Although scooby is eating and drinking.  

Answer
I have never heard of a sudden death like that. The only way I know od sudden death is if the other one killed him, but you would have found wounds, and it sounds like they loved each other. I have no idea in telling you what happened. The only way to find out is find a geunia pig vet and do an autopsy. I would carry the other piggy to the vet and make sure she is good and healthy. I am so sorry I couldent give you an answer. Let me know if you find out what it is. Thanks.