What does "episode of sub" mean here?
Native speaker’s answer
Rebecca
Here the word "episode" means a limited period of time that a person is affected by an illness. In this case, the mental illness of psychosis. You should also treat "sub" as a prefix. Which means not quite, almost or nearly. It should be attached to psychosis, "sub-psychosis". Ex: The weather feels sub-tropical today. Ex: She use to have more episodes of epilepsy when she was younger.