Post-traumatic stress

You may be looking for the novella Shell Shock.

Post-traumatic stress disorder, also abbreviated to PTSD, and occasionally labelled as shellshock, was a psychological condition, caused by suffering a traumatic experience and being unable to cope with it. Symptoms included becoming anxious, prone to physical illness or increasingly withdrawn. It could also led to heightened sensory awareness where a person's senses became more alert as something related to trauma drew nearer. (PROSE: Empire of Death, The Glamour Chase)

Many soldiers who fought in World War I suffered from PTSD. As the condition had not been diagnosed at the time, it was referred to as shellshock and was often erroneously thought to be nothing more than soldiers displaying cowardice. WWI veteran Oliver Marks developed PTSD in the inter-war years when he was attacked by the Tahnn and witnessed the death of his fiancée Daisy Conlan. Rory Williams lamented that even by his native time of the early 21st century, so little was known about PTSD that it was tragic. (PROSE: The Glamour Chase)

Tommy Brockless suffered from shell shock due to the trauma he experienced while fighting in World War I. (TV: To the Last Man)

Reggie Mead was suffering from shell shock when Amelia Doory first met him in 1915. (AUDIO: Project: Twilight)

Jacques Fournier suffered from PTSD after leaving the French army. Counsellor Dr Sophie Rousseau treated him with hypnotherapy. (AUDIO: Uncanny Valley)

The Fifth Doctor hypothesised that Nyssa was suffering from post-traumatic stress disorder as a result of Adric's death. (PROSE: Empire of Death)

Professor Geoffrey Thynne specialised in post-traumatic stress. (PROSE: The Touch of the Nurazh)

Quell suffered from post-traumatic stress following his time as a soldier. While working as the captain of the Orient Express, this mental affliction was identified by the Foretold, leading it to target and kill him as the weakest remaining passenger. (TV: Mummy on the Orient Express)