Hello Nike007: If your brother simply won't seek treatment, & your mom doesn't see your brother's situation as being a problem, then there really is nothing you can do, except to assure your brother that you will be there for him if-&-when he needs you. Nor are you responsible for him. Your brother is a minor &, to the extent that someone is responsible, it is your mother. This is not a matter of you saying "screw him". It is simply the reality of the way things are at the present time.

From my perspective, all you can do now is to be there for your brother if-&-when he wants help. Then, perhaps, you can be of some assistance to him. But, in the meantime, it is important that you not allow your brother's situation to aggravate your own mental health issues. If you do, then you may be less able to able to help him if-&-when the time comes.

You mentioned that you see a pdoc. Do you also see a therapist? I would encourage you to talk, in depth, with a therapist, or other mental health professional, about your feelings regarding your brother's situation. At the present time, the greatest gift you can give your brother is to take good care of yourself.