The physical dependence of cocaine can make it very difficult to quit on his own. Good that he has done it before but sounds like he is having a go at it right now with pushers after him. I’m sure that alone is causing him some serious stress and leading to more self-medicating, worsening his schizoaffective symptoms. Is he on any antipsychotics? If so, then that means he has a pdoc. His doctor may have some pharmacological suggestions that could help him through the process of withdrawal.