That sounds pretty terrifying. Another reason for me to stay away from Peru, as interesting as the environment sounds. Luckily safer substances and ROAs can go just as deep as ayahuasca minus the negative side effects.
Ayahuasca is pretty much a combination of two substances, DMT and a MAO inhibitor, and then some random stuff depending on what shaman you're with. The MAO-I basically allows the DMT to become active when ingested (as opposed to smoked or injected), but it also creates the risk of serotonin syndrome, the symptoms of which sound like what you're describing.
If that's what happened then the weed experience seems confusing though, since it can't trigger SS. I've had some "negative" experiences with weed to say the least, but I never really passed out. I got close once when my entire field of vision got filled up with tiny turquoise colored donuts and my legs felt like gummy snakes. Somehow managed to get home and just lay down. Other times I've paid too much attention to my breathing and/or heart rate and freaked myself out into believing I was dying, but never anything quite as extreme as what you've described. Absolutely zero negative experiences with harder drugs beyond the usual "did I take too much" or "was this a mistake" kind of thoughts that accompany the come-up of every great trip, at least for now (fingers crossed that won't change).
Have you talked to your doctor about the SS possibility regarding your current condition? Or was that unrelated?
Yes I would suspect the MAOI interacted with something to cause to SS. I might not have followed the preparation diet as strictly as I should have, especially considering the giant dose I was given which measured about 1 Liter when I now see that most people drink about a small teacup's worth. In addition, I have a genetic SNP called the "warrior gene" which already impairs my MAOA function.
By the way, in the indigenous culture, ayahuasca is not actually MAOI + DMT. It is strictly the Caapi plant (the MAOI) which has the name Ayahuasca. Other additives, such as a DMT source, or other things, may or may not be added. Most of the time they were not and it was just the Caapi. Also, in most healing ceremonies it was actually just the shaman who drank in order to channel energies to the patient and the patient did not even drink. I learned all of this after the fact. So apparently all us tourists are being taken for a ride.
I did not get ill with my current condition until 2 years after this event, so I'm not sure how I would bring up a correlation with my doctor, unless I want to hear that I'm suffering from a somatized PTSD disorder. Actually I'd be curious to do a SPECT scan of my brain and see if anything died.