Schizophrenia

I have recently been told that my younger brother is being evalutated and assessed for schizophrenia.
He tells me that he hears one voice and it is outside of himself. He is currently on medication and it seemed to work for a few weeks but now he is back to hearing this voice and is very depressed.
I am unsure of how I can give him the support he requires to maintain his fight against this disease and stay strong. I can sympathize and support him through the depression as I, myself am Bipolar type 2 but I am very unsure how to go about supporting him with being schizophrenic. Its scares me cause of the stigma attached to it, I dont want to see my brother suffering.
I am extremely scared because hes has in fact not be diagnosed, which gives some false hope, however, he still hears this voice. He is a very intelligent, social 19 yr old who does not do recreational drugs or drinks.
Any suggestions would be greatly appreciated.