We have had our guinea pig for about a year now. We take good care of him, and clean his cage every week. We have never had a problem with odor at all, there was a slight odor when cleaning the cage but it was very slight. We use carefresh bedding. In the last 2-3 weeks there has been a terrible odor, really, really, bad. We have had to clean his cage every 2 days and it is still bad. Does this mean he is sick? He seems normal in behavior and there is no noticeable injury on him. He is alone in the cage and gets lots of TLC every day. I don't know what to do but we have to do something. Something has to be wrong as this has not ever happened before with him. He is around 4 years old.