My son's mental health

My eldest son Peter (35) has been suffering mental illness and depression since early chilhood. He has developed facial pain which has doctors mystified and unable to help. He has lost hope and faith in God and says there is no God and tells me not to pray because there is no God. I am struggling to cope with this and my own faith is coming under terrible strain. Please pray for him and I Thank you and God bless you Jesus I am trying to trust in you but am so weak.