A 25-year-old female presents with a depressed mood, decreased interest in activities, difficulty making decisions, and feelings of worthlessness. She reports these symptoms always worsen just before her menstrual period and improve a few days after the period starts. What is the most likely diagnosis and next steps?
The patient's symptoms and their timing suggest a possible diagnosis of premenstrual dysphoric disorder (PMDD), a severe form of premenstrual syndrome (PMS) where symptoms are severe enough to cause significant distress or functional impairment. The next steps include ruling out other conditions like a major depressive disorder, using a symptom diary to confirm the cyclic nature of her symptoms, and discussing treatment options. These could include lifestyle modifications, cognitive-behavioral therapy, hormonal treatments, or selective serotonin reuptake inhibitors (SSRIs).