It does sound like he has the positive symptoms of Schizophrenia. Does he have any other symptoms at all? like lack of emotion, social isolation ect..
If he has smoked pot for along time then it maybe that he has got Cannabis Psychosis and not Schizophrenia but i guess only a qualified person will be able to give the correct diagnosis.
The best thing you can do is try and be there for your brother, wether thats telling him that your only a phone call away, going to see him at weekends or giving him a call once or twice a week.
Suffering from the same sort of thing myself all i can say is treat him like you normally would, dont treat him differantly as it often makes people feel worse.
I hope he gets it sorted out.