Question

A 28-year-old woman, G1P0, at 14 weeks gestation presents to the outpatient clinic reporting severe anxiety, insomnia, and a persistently depressed mood. Eight weeks ago, she was the victim of a violent armed mugging. Since the event, she has experienced recurrent, distressing nightmares about the attack and feels intensely fearful when leaving her home, constantly scanning her surroundings for threats. She actively avoids the street where the mugging occurred. Her psychiatric history is significant for Bipolar I disorder, with her last manic episode occurring at age 22. She was previously stabilized on lithium but successfully tapered off the medication under medical supervision six months prior to conception. She is currently taking only prenatal vitamins. Vital signs are within normal limits. Recent routine laboratory studies show a normal complete blood count, a free T4 of $1.2$ ng/dL (normal: $0.8-1.5$ ng/dL), and a TSH of $0.2$ $\mu$ U/mL (normal: $0.4-4.0$ $\mu$ U/mL). The patient is desperate for relief and asks for 'anything that will make this stop.' Which of the following is the most appropriate next step in the management of this patient?