Diphenhydramine and fluoxetine actually have major interactions, but they do not match the reports about how Nex died at all. The combo has a significant risk of causing serotonin syndrome, this would practically be a given in case of an OD, and serotonin syndrome is, among other symptoms, marked by a highly agitated, confused state of mind, an often dangerously increased heart rate, muscle spasms and cramps, sometimes also diarrhea and vomiting and especially symptoms of hyperthermia like fever and profuse sweating, as the constant muscle spasms make the body temperature rise to life-threatening levels. Serotonin syndrome sends the entire body into overdrive, potentially fatal cases are a very, very noticeable condition. Especially when somebody is known to be on an SSRI like fluoxetine, serotonin syndrome should come to mind immediately, would be easily diagnosed by looking at the symptoms and could then be treated accordingly.

The sudden, spontaneous collapse that preceded Nex' hospitalization and death doesn't match this at all. An overdose of diphenhydramine would also already be guaranteed to cause a state of hallucinatory delirium on its own, but this wasn't reported by Sue Benedict, either. Nex' grandmothers' account of how they died doesn't match this toxicity report at all. This is an obvious cover-up story, just as the entire case has been dismissed and covered up by all authorities involved ever since the bathroom fight.

Nex Benedict didn't kill themselves. They were murdered by three girls at their school and the state government of Oklahoma is making a piss-poor attempt to hide this truth from the public, because they enacted the very policies that encouraged the murder.