sounds to me like your brother is using again too and if he continues, it may not be long before he's back to where he was before. just give it time, then you will know the answer to your question, there's nothing you can do about it anyway. i think he may be substituting one drug for another and usually even that will lead back to the drug of choice.
i'm a recovering addict, for me, i CAN'T drink and i'm the first one to let any doctor know that i DO NOT want anything prescribed for me that's addictive. i agree with liesagain.