You are going to run out of genres of movies to compare drugs to if you continue to use drugs recreationally. Physically, I have no idea what a high dose of antihistamine could do to you exactly, there's no telling to be honest. You will likely just end up laying in bed, being scared shitless. What's fun about that? With a horror movie, you know it's not real, you know you aren't in that horror movie. I don't think you understand delusions exactly. You won't enjoy being trapped in that horror movie.
I guess you haven't dosed edibles high enough if you find them uninteresting.
We can't tell you what to take to get high, we just try to minimize the harm done by taking drugs.
You remind me a lot of myself, minus the fact that I had access to a plethora of drugs when I was 17. I wanted to try everything that I could get my hands on. That ended up with me finding opiates and becoming addicted to opiates for years. Look on the top of the page under personal accounts of addiction. Realize that this is what game you are getting yourself into. A lot of us would sell our soul to the devil to say that we never experienced these various substances and here you are with this mindset. Seriously, read that thread and think do you want to really do this to yourself.