What is the effective treatment for someone who believes his mother is bewitching him and ordering him to leave the house while he is ill?

One must be dutiful and kind to their mother, in word and deed. It is not permissible to abandon or shun her. It is forbidden to accuse anyone of sorcery without clear proof, so how much more egregious is it when the accused is one's mother? This is slander and a grave sin. What you feel may not be sorcery, but rather delusions. The cure for this is obedience to Allah, dutifulness to one's mother, and consistently reciting the Quran and the morning and evening remembrances (adhkar).