I hope this message finds you well, present circumstances excluded. If you have not contacted the California Department of Corrections, you need to file a formal complaint with them so as to exhaust all administrative remedies. The next step you need to take to assert exterior pressure and perhaps even garner expert legal assistance free of charge is to contact the American Civil Liberties
Union (ACLU) in California and explain the situation with them and ask for assistance.
The ACLU will likely contact both the jail as well as the Department of Corrections. That is one reason it is important that you have also contacted both of those entities.
You need to have a game plan as to what objective you want to accomplish when you contact the ACLU or any other entity. What are you trying to accomplish? It sounds like segregation in view of the illness and treatment, it sounds like treatment (perhaps chemically as well as through counseling) and you also want the unconstitutional cruel and unusual punishment to stop immediately.
As a means of last resort, you may need to petition the court that convicted him for an order to move him from this correctional institution to another that is better suited to handle an inmate with these particular mental and physical issues.
So, in summary, start by filing a formal complaint with the department of corrections. Then, you need to contact the ACLU and request assistance. As a last resort, you may need to petition the court of conviction for a change of facility to accommodate his needs.
Let me know if you have any additional questions or comments.
Best wishes going forward and you are to be commended for your willingness to help this person.