Search the web sites under disability assistance, advocacy, etc. The role of agencies seems often to keep people out rather than help them. Their treatment can often be humiliating. I prepare myself as much as possible before seeking their services and have good support to turn to afterwards. They are there to help those in need, but many of them have become hardened and expect that most people are just out there to take advantage of them.
Some people look at applying for assistance as degrading.
It is a practical tool for survival. It can give you the security and support you need to take care of your illness, and help to provide the road to recovery. The best help will be gained one to one with people in your community. Talk this over thoroughly with your doctor, disability advocate, and members of support group. Find someone to help you when you fill out your application, or review it before submission.