Mrs. B 36 years old, married, seller, lives in Kandal province come to emergency because of suddenly emotional disturbance for 2-3 times/ month, such as: perspiring, heart palpitation, difficulty to breath in (dyspnia), difficulty to control this emotion and fear of dying for around 4 weeks. she had BP= 130/80mmgh, Pouls= 102 /mn, other medical investigation reveal no abnormality related to the medical illness noted. What is the probably diagnosis of this patient: