I just got back from a 1 week vacation and my female guinea pig Toby seems to have lost weight. I have never weighed her before but she is noticeably thinner and lighter. My next door neighbor cam over everyday and changed the water and filled the hay and pellets if needed. My other guinea pig pippin is also a female and has not lost or gained any noticeable weight. I fed both of them lettuce and cleaned their cage. They both ate but Toby ate slower than normal. Whenever I open the fridge door both piggies normally squeak as loud as they can and Toby is always the loudest. When I opened the fridge today, Toby made a feeble few squeaks. She also has a few crusties in the corners of her eyes. Is Toby sick? If so is there anything I can do without taking her to the vet and should I separate them in case of sickness spreading?