This is not part of "The Final Cutie Mark Crusade" storyline; it is however part of the "Asylumverse" storyline created by Daemon of Decay. (Yes, I have obtained permission from him!)

After an incident near Ponyville, Phalanx Spear is knocked unconscious. When he wakes up in the barracks, he talks to his fellow guards, but after a minute starts assaulting them, apparently terrified. He is admitted to Broadhoof Memorial Psychiatric Hospital, where he is now an inpatient being treated for Post-Traumatic Stress Disorder.