You could try a clinic. Here most clinics go on a sliding scale according to your income for how much they charge. It sounds like to me that you got the psychotic symptoms under controll, but it sounds like to me he is still having mood issues. I think a mood stabilizer may help his mood you should talk to his doctor about it. I hope you get everyhting worked out.
Sometimes a change of medications can help, something stronger or different. I would take him back to the psychiatrist, kicking and screaming if you have to. There are other medications like lamotrigine, lithium and depakote (mood stabilizers versus antipsychotics) that may also be helpful. It is more common now to treat with an antipsychotic alone, but sometimes a combo can really help too.
I don't know what indigent health care is but I know bipolar disorder qualifies for medicaid (I think that is what you call it in the US or is it medicare - disability coverage). I know some people on it for bipolar, and that would get him medical coverage, and a little bit of a stipend each month. Enough that he may be able to live in a group home if it comes to that.
There is a good book called The Bipolar Survival Guide 2nd edition (make sure you get the 2nd edition as it has the most relevant meds in it). It may help him come to terms with what is going on, and wouldn't hurt for you to read as well because it goes through the theory, meds, social rhythms. It really does have it all in there. I think most book stores will have it. I got mine on Amazon, but you may not want to wait 2 weeks to get a copy.
I can only sympathize. I have been to hell and back with my own rapid cycling bipolar disorder, which I have had since a young teenager. I am now dealing with the system and trying to get my newly diagnosed teenage son treatment too. I am dealing with punched walls, doors, extreme overreaction and no treatment program yet.
They are only making an effort now because my own doctor sent a letter with how I presented at that age because I went untreated until my twenties. I have a an assortment of medications I take but I am still cycling constantly. Living with my son at the moment I don't know which version I am going to come across. I just wish there was more I could for him.