[therealx]

The whole thing really reads as mental illness to me. I bet he had it under control for the most part, but things worsened as the trip went on.

One of the biggest reasons for quitting mental illness drugs is due to the feeling that everything is "OK", and they don't need them anymore.

This almost universally false, and as the drugs leave their system, things get progressivelly worse over time. The story fits this timeline really well.