Well the thing is that these molecules interact with all organs in your body via the bloodstream, the nervous system, and indirectly through the stimulus of other organs. An antipsychotic is never only involved with your cerebral organ, but all the rest.
If you have a nice psychiatrist, I think it would be worth asking them, as the question of the heart is both complicated and important. It involves many interacting organs/systems and some detailed anatomical knowledge.
Do you have a watch with an EEG? I think that is be a great way to get a realtime visual reading of your QT interval, and the watch will also 'get to know' your QT interval/heart habits across time so it'll have a good baseline of data to judge by.
As for serotonin syndrome, from what I can gather, it's generally difficult to trigger without a MAOI in the mix. Usually it would be a mix of drugs that cause it: MAOI, with a strong SSRI, or I think maybe a MAOI with a regular SSRI, and a Serotonergically mimicking drug itself, but without MAOI it's way less likely, and all your drugs largely avoid Serotonin if not completely so the SSRI function is also very minimal as is for you if you were for instance, to take Mushrooms.
but
I don't know that much about how the rapid onset of DMT would affect you. It's complicated because without MAOI and SSRI's present, the only way the DMT could be lethally contraindicated with your meds would be via a more indirect, wholistic interaction which I am unable to assess. It's true that some of your symptoms are shared by serotonin syndrome.
// *sips quadruple espresso
You might also want to consider testing slightly different thermal conditions. If thermal balance helps you out, it might not be serotonin syndrome. The psilocybin will relax you, which will lower your blood pressure
and thus, body temperature.
As you get colder, your body might try to heat up using adrenaline, but the adrenaline could be partially (even if only indirectly), blocked by antipsychotics, causing your body to release more adrenaline to achieve the same effect. Now you are sweating due to excessive adrenaline which is ineffectively raising your body temperature ~ due to the blockades by the antipsychotics or whatever. This excess adrenaline now revs up your heart. Your body tries to constricts to heat up but it can't. This is just one random hypothetical chain of events in my brain.
So Fire says, hey! get a warm blanket and put it over yourself for 10 or 15 minutes. See if raising your body temperature lessens your adrenaline response, because it fixes the doubly low body temperature issue caused by the fact that psilocybin and the antipsychotics both act to chill you out.
*sips more coffee*
Body temperature, sweating, vasodilation/constriction, heart rate, metabolism, PNS and SNS activation, etc all ~ literally everything ~ is interconnected and in one movement. Your concern about the heart rate, the stability of the hearts function, the clammy cool sweats, adrenaline anxiety, etc all of that requires a complex analysis. I really don't know and can't help you come to any knowledgeable, reliable, dependable conclusions like a professional psychiatrist (or internal med doc) would.
Thermo-dysregulation goes DEEP, since thermoregulatory reflexes of the body are one of the THE most central survival mechanisms.
Serotonin syndrome also is quite deep. Both phenomena are very complex and wide reaching.
My brain can't really function today anymore xD
Those drugs in your system could literally, be giving your body mixed signals about what is thermally happening. causing certain parts to modulate blood pressure inappropriately, which the body might tries to rectify with adrenaline, or something. idk it's just complex xD They can effect the contractile capacity of your muscles themselves. Dopamine blockade can for instance, extend your QT interval. Crazy stuff. I would have to double check whether that applies to your dopamine blocking medication however. But these are all significant in the analysis.
cardiac is another word for "everything"
What the heck am I even saying anymore. I can't focus on caffeine
Sry please forgive me!
You should especially not be on a dopaminergic blocking agent for any extended period of time. I'm a very antiantipsychotics person F Y I .
of which divine beings are ever clearer and closer expressions of.
). In the west we have esoteric mystical societies that do a good rational job of talking about some of these things, but ultimately, spiritual law is learned through physical, mental, and spiritual challenges all (which are all the same but you know what I'm saying. Speech itself is artistic 
)