Did you take any other drugs?
I've experienced stuff like that at high LSD dosages, but it wasn't unpleasant. In fact, I liked it. It's what I meant by "ego death".
That is, there's no awareness that an "I" exists. There's just stuff happening. Inside, outside, all the same. Just stuff.
And then gradually, there's this internal dialog that starts talking about all the stuff. That is, consciousness, what I'm calling ego aka "I".
With marijuana during LSD peaking, that happens abruptly. With sometimes considerable anxiety.
For the most part though, my small experiments (LSD, mushrooms, DMT) have had a very positive and borderline revolutional effect on my outlook on life. Only time I've had negative experiences have been on mushrooms, both LSD and DMT have always been positive.
The proper path is to wean yourself off of the antidepressants for the experience, and then only undertake the experience with an experienced sitter or guide.
Psilocybins effect is enhanced by MAOI and decreaces by SSRIs. LSD effects are decreased by both. With other other psychedelics you have to be a bit carefull.
You probably think of MDMA and MAOIs, this would be a dangerous combination.
And indeed, that's what ayahuasca (aka yage) is.
Plus various mushrooms and other psychoactive stuff, depending on the preferences of the curandeiro/a (shaman) and the intended outcome.
SSRIs, do not mix.
NDRIs, lots of people report they're fine.
Hopefully we'll get better data on what other chemicals are okay to mix as these things slowly become permitted to be the subjects of study.
Later, I used to vacation in Amsterdam for the shrooms. But I'd go off the SSRI maybe a week or so before the trip.
I take the SSRI Fluoxetine (Prozac) and have tried numerous psychedelic drugs while on that prescription drug. Before doing so I checked with my psychiatrist who did not believe there would be a great risk.
My experience has generally been that psychedelics work (with the exception of MDMA) and there are no drawbacks to using them while on an SSRI. Of course, psychedelics do have risks and educated, responsible use is appropriate.
But they're really very different experiences.
Alcohol does accentuate psilocybin, acceptably.
But combining marijuana with either, especially LSD, can be frightening. Your short term memory drops to a few seconds, so you can forget who (or even what) you are, where you are, etc. Some people panic, and fear that they'll never be sober again.