Guinea Pig -- died

Question
My son has had this guinea pig for 3 1/2 yrs.  She has always been very healthy.  Yesterday, tho, he went to take her out to play (he's very good with g-pigs and gets really attached), he found her lying down (dead) in her cage. Needless to say, this really freaked him out.  I went over to be sure he was correct, and she wasn't just sleeping.  He wasn't mistaken.  I took her out, and noticed that there was blood in her bedding throughout the cage???  
Question:  What could have cause this?  Did she just age, or could there have been something else wrong??

Answer
Hi Mae

Firslty, I am sorry for your loss, and please pass on my sympathy to your son.

Its really hard to say what happened here but it certainly wasn't old age. I tend to think that she got attached or bitten by something. Is this a possibility based on where you live. A spider or rat etc?

Could you tell me if she had an visible wounds or where the bleeding appeared to be coming from on her body.

Thanks

Andy