A 30-year-old male has presented to you today reporting that he has had difficulty getting to sleep recently. On further questioning the patient informs you that he is scared to go to sleep because he has been experiencing flashbacks from a RTA a few months back. He also reports that he is finding it difficult to get in his car and drive to work and has been taking the bus. His wife who is with him also states that they are having problems in their relationship and that she is worried about him. What is the most appropriate diagnosis?