The Legal Aid Society of San Diego, Inc. (LASSD) is a nonprofit law firm that provides free legal services to lower-income San Diego residents. They assist with health, housing, family law, immigration, and many other legal matters.
They also offer multiple free clinics covering a range of topics (i.e. evictions, taxes, restraining orders, etc.), which you can explore here.
They have three different locations in San Diego and you can learn more about their services and if they are able to assist you here.