Boi looks so much like my mom's, yodi! He passed away last year. She loved him dearly. I once babysat him for a week, while she and bf went to Texas for a family wedding.
He hurt his eye right before she left, and no one knew. That night, when I went to her house to check on him, he was sad and withdrawn and walking very slow. At first I thought he was depressed, but couldn't get over feeling it was more. Decided, that if he didn't seem different by morning, we would go see the vet. He had a scratched cornea from a squirrel chase, and he would lay just as still as could be on his back, in my lap, and let me doctor his eye, and then we would curl up in chair, and nap.
I went down there about five times a day, and stayed for hours. We became very close, and he was doing well, when mom got back. I did call her, and told her about all of it. She knew I would take good care of him.
anywhoo, I can only imagine how you feel. This seems rather sudden. Did your landlord sell out? I hope for your sake, and Boi's, that your sister can take him. These are some precious little dogs. :D