Not following you very well; this fellow who's in trouble is a friend of your brother, and he's having PTSD issues from the forces. Correct so far?
Who's in Chicago, your brother, the PTSD fellow or both?
If the PTSD fellow isn't in Chicago, where is he?
Is the fellow American or Australian, and did he serve in the US Armed Forces or Australian? Has he tried to contact his Veterans Affairs people?
Unfortunately if he's Australian, and served in the Aussie Armed Forces, he may be SOL if he's trying to get help here in the US. He'd probably have to turn to the private medical sector, and if he doesn't have a job or insurance, he'd have to come out of pocket for the counseling & meds, and they'll be outrageously expensive.
Sorry to say, but that's just the way our system works over here. Many people here in the US are experts at "working" the welfare system, but the ones who are truly down on their luck, and need help, tend to fall through the cracks.