Hubert goes into chill mode

My son started college away from home and, it seems, Hubert hasn't been the same since. He just mopes all day long and lays on his bed and just goes out to poop. He is also a lot less vocal these days even when he's hungry which isn't often. His food often goes uneaten (never his fresh fruit or peanut butter, however). We'd be worried but he really hasn't lost any significant weight. Of course, just laying around how much weight can he lose. He used to like being stroked with a brush; often lying down immediately so as to give access to his belly but that's a thing of the past.

We suspect that he may be sight impaired because he gets awfully close to objects before sidestepping them. He seems to be using his sense of smell to guide him. When walking along a paved narrow walkway, he will swing his head from side to side as if he's smelling either side of the walkway.

I want the old cantankerous Hubert back.