Psychotherapy is very different to psychology. Psychotherapy is much more old school, classic conversational therapy as derived from Freud. Here in the UK (but much less so in the US) it has a poor reputation as unscientific and with weak research evidence. Psychology is generally a more experimentally driven, more science based approach, and shouldn't be lumped in the same category. Essentially, psychological treatment can help when psychotherapy has not; all the same this appears to be physiological rather than mental.