I get full blown hallucinations when coming down off of a binge. I was on it for almost 20 hours from 8:30 AM until about 4 AM the next day and went through about a gram of mandy and a pill on Friday and by about 4 AM (Saturday morning) when I was starting my comedown I was seeing faces completely differently. A girl I was with changed her hair about 4 times throughout the night and every time she did she took on a completely new face, and then she started cycling through faces of folk singers from the 60s, like Joan Baez and Melanie Safka etc, etc, then she turned into my old Spanish teacher, then she just turned into someone I've never seen before, and changed ethnicity and gender a few times too, I was hearing shit too, like I came home and watched a film and it kept going really low-pitched and sounded like a voice slurring more and more until it shut down like a machine or something, so compared to that blurred vision and ringing isn't so bad. I also had my vision go dim when I got up as if I was about to pass out, although I never actually did. Never had the pounding heart with MDMA but I get that with amphetamine and methylphenidate comedowns. Re dosing (in my experience) tends to make comedowns last longer, but I don't see why for someone who experiences the comedown differently it couldn't just make it worse. Since it's your first time as well that might make it worse, not because it actually is worse, just because you're not used to it.
My understanding was that SSRIs like Zoloft make MDMA completely ineffective, maybe you didn't get real MDMA, or maybe I'm just wrong, but either way, Zoloft shouldn't really make the comedown worse.
My advice is to just go to sleep. If you think you've got high blood pressure and you can get benzos, then you could try that, but if you're feeling like you're almost passing out then it could actually make you pass out, so honestly just keep your phone nearby in case anything happens. Usually, if I'm fully conscious and able to walk, I just hang about near the hospital if I think I've fucked up, but it doesn't sound like you're in dire need of any medical attention, just on a shit comedown.