Final answer:
FF McMillan is most likely suffering from Post-traumatic stress disorder (PTSD), which is an anxiety disorder triggered by a traumatic event such as the death of a colleague on the job, leading to a variety of symptoms including emotional outbursts and respiratory difficulties.
Step-by-step explanation:
FF McMillan, who is displaying signs such as rage, respiratory difficulties, and sexual disturbances following the death of a fellow firefighter on the job, is most likely suffering from Post-traumatic stress disorder (PTSD). PTSD is an anxiety disorder that can develop after a person is exposed to a traumatic event, such as the death of a colleague on the job. Signs of PTSD can include intense emotional reactions, recurring distressing memories or flashbacks, difficulty sleeping, irritability or outbursts of anger, and hyperarousal symptoms like breathing problems. Psychological trauma and its consequent symptoms including PTSD have been historically evidenced in war veterans, and similarly, the distressing nature of a firefighter’s job can expose them to traumatic events that can lead to such disorders.