I'd say put it on a skewer and grill it but that's not very nice.

Found This Online:
Guinea Pigs are very susceptible to the human cold/respiratory virus. If the caretaker has a cold or virus, precautions need to be taken to safeguard your guinea pig. Increase the Vitamin C intake of the guinea pig and avoid all contact if possible. If you cannot delegate the care of the animal, avoid breathing, coughing or sneezing on or around the guinea pig and do not handle the animal. Wash hands before handling any food or equipment. If the guinea pig has a discharge from the nose or eyes, has labored breathing (sides appear to sink in and out with each breath), has little or no appetite, you must start using an antibiotic available from your vet.