Guinea Pig is sick.. please help

Question
My guinea pig Annabelle is almost a year old, and she isn't eating.
She's gotten skinny, wont move around at all, she has diarrhea and she's breathing pretty fast.
I've tried taking her outside, She just lays down.. Tried to feed her an apple, she bites it, but then doesn't chew..
Last night when I went to say goodnight to her, her right eye was glazed with mucus and so was her nose and her underside was dirty with feces and urine..
My parents don't want to take her to the vet because she's 'only a guinea pig'..
She means so much to me, and seeing her like this is breaking my heart..
So I ask you, please.. help me find out what's wrong?

Thank you

Answer
Oh Emmalee I wish I could say something that would make this better, but I'm afraid your little Annabelle is gravely ill. At this point not even your vet would be able to turn her around. Guinea pigs don't give us warning that something is wrong. They hide their illnesses until they've reached the point of no return.

I can't tell you why this happened, just that it's happened to all of us and we all know exactly how you feel. When they get to the point that they refuse all food and drink they are trying to tell us they're going to cross the Rainbow Bridge.  

I would give anything to have an answer and a fix for Annabelle, but honey there isn't one. I am so sorry.