When i was in 5-8 grades i was given SSRIs which i definetely believe is possible caused this POIS, now considering what SSRI are capable of doing considering at most severe PSSD can cause total anhedonia, cognitive dysfunction ,brainfog etc..
I just thought it is worth saying and if someone has some similar story...could share it down below but that's the main thing i was given ssris around the period this thing started