A 35-year-old female reports heart pain (aching and drilling) occurring mainly in the morning in autumn and spring and irradiating to the neck, back and abdomen; rapid heartbeat; low vitality. Occurrence of this condition is not associated with physical activity. In the evening, the patient's condition improves. Study of somatic and neurological status, and ECG reveal no pathology. What pathology is most likely to have caused these clinical presentations?