My first comment would be to get him back to a Pdoc ASAP. A GP is great for "general" health issues. But for mental health issues, especially those that involve delusions, a competent pyschiatrist is needed.

That being said.....in the beginning Effexor gave me such vivid dreams that I could not sleep. I now take all me Effexor XR in the morning.

Good luck to you and your son.