Stimulants, and in particular sleep deprivation from stims (not implying that was you, it's just a common pattern), compounds delusions really hard. Make sure if you continue to take stims you eat good, sleep a lot & drink a healthy amount of water

ADHD even without medication can make you hyperfixate on something for so long (usually if it's encouraged by environment) that you end up literally having not to think of it for a time if you want to recover your skill. Autism, excessive routines, isolation, lack of play and chaos helps make this happen too.

I‘d actually suspect the Dexedrine as the root cause of the psychosis.

Why?

Dexedrine is powerful. I took that when I was a teenager for ADHD and I lost tons of weight down to maybe 140 and it drove a strong compulsion for more drug seeking. I also got straight A's and started my own website business, but I also would have terrible fights with my mom and got kicked out of my house.

I think you may be able to attribute a lot of your experience to that drug.

When I switched to Adderall, my entire life changed and things started feeling normal again.