My Guinea Pig's only eating carrots?

I'm really sorry for your loss. My two guinea pigs just died within two months of each other (they were like five or six and both developed untreatable conditions) and I really miss them, so I understand how you're feeling. But as for Chewit, if a guinea pig doesn't eat for like 12 hours, then its whole digestive system can start to shut down, which is a major problem--and its healthier for them to pretty much be munching continuously anyway. So I wouldn't take away his treats if that's the only thing he's eating. Get him a new buddy. Until then, however, you can try blending some of his favorite treats (carrots?) and normal piggy food in a blender with some water and feed it to him through a syringe. If you don't have any syringes on hand, you can use a medicine dropper, eye dropper... Just make sure you rinse it out REALLY well first if it was used for something a piggy shouldn't have. Give him TONS of love and attention and maybe it will help him get over the loss of his beloved brother. Also, you might want to talk to your vet because if he's not eating, he could be sick. Good luck! I hope Chewit starts to perk up.