My guinea pig has recently lost its squeak

Question
I've had three guinea pigs for about 21/2-3 years now and recently one died because it stopped eating. Now the other guinea pig- about 4 days after the other died- has lost its squeak. It was always the loudest and squeaked whenever anyone came near the cage. Now when i come near the cage, i see it trying to squeak but just cant get anything out. It still seems to be eating- however it looks a little smaller than it did a couple weeks ago. Is it dying? Could it be related to the other guinea pig dying? We thought it might just be a cold so we've been giving it extra vitamin C. Is there anything else we can do? The third guinea seems perfectly fine.

Answer
These are the hardest type of answers I have to give and the ones I hate doing the most, only because I know you want something positive and comforting but that's just not always possible.

Guinea pigs age at different rates, just as humans do.  Some will live for up to six or seven years, others get old and pass way sooner. We can't predict who will pass when, and sadly when we lose a pet that just seems to die too soon it's so hard to understand.  

One of the signs of aging and preparing to leave us is weight loss. Guinea pigs don't get colds, and even if they do Vitamin C is not a treatment for anything. In order for vitamins to work they must be taken on a daily basis to help our immune systems stay healthy.

Vitamin C is pure ascorbic acid. It promotes good bone strength and health, but if given in large amounts it not only doesn't make us better, it actually can cause harm. The ascorbic acid can eat the membranes in the stomach and cause an ulcer. So taking large amounts to try to cure something is not wise.

As for losing her voice, she may well be getting weaker and ready to pass away. This has nothing to do with the other pig dying. It's just the normal course of life. Life is only temporary for all living things. We're here such a short time. For some that time comes quickly.

I know this isn't giving you the comfort you hoped for and I wish I could honestly say everything is just fine. But I would not be giving you a fair and responsible answer if I did so.  I think you are probably right, her time may be getting close.