One of our 2 guinea pigs is ill. It started just around Christmas - she suddenly became very quiet and developed a droopy red eye. We took her to the vet, who suggested infection, gave her antibiotics and eye drops. After giving her eye drops second time, she became unsteady on her feet and gone off her food, with just weak nibbling. Took her to another vet, who suggested overgrown teeth, trimmed them. She is still not eating and still wobbly on her feet. We give her water and her favourite food, but she is just nibbling. She has not lost weight yet, but just no herself anymore.... There is probably nothing we can do anymore, but she is only 4 years old...