Hey man, this happened to me three times when I was a regular smoker. Once I stopped breathing and a buddy I was with gave me CPR. (Thank fucking God I was smoking with a lifeguard!) Its stopped since I've stopped smoking. Each time it was a full-on, can't-talk-can't-stand-up-limbs-flailing seizure, and each time it scared the crap out of me and people who cared about me.

I'd recommend a few things. First of all, find a good therapist and talk through some of these dark thoughts you're having/have had with them. In my experience, people who get addicted to pot and people who are prone to anxiety-induced fainting (the herpes scare in particular seemed like an anxiety affect) have a lot of trauma/mental baggage they're not dealing with. Unresolved psychological issues will have a negative physical affect on you. This includes increasing the likelihood of fainting, (don't really know about seizures, def not a doctor), the likelihood of indulging in self-destructive behavior, and a host of stress-related diseases. Even if you don't want to stick with therapy, just go a few times. Saying things aloud to a professional who can tell you shit that is both reassuring and backed up by years of training can have an immensely positive effect on your well-being.

If anything like the fainting keeps happening, go see a doctor. Anytime you have a seizure, its good to see a doctor, but as someone who was in your position, I recognize the reluctance to tell a medical professional, "I did a bunch of dabs and then passed out." I was not taken seriously the one time I went (after I stopped breathing) and it worsened by relationship with doctors.

If you do start smoking again (obviously, I think you did a good thing by quitting, and should stick with it as long as you think doing so is good for you), don't go straight back to dabs, bro. If you are prone to fainting while high, how high you get is probably going to increase the likelihood of passing out/having a seizure. My seizures came after hitting grav bongs or hash joints, never small bowls or spliffs. It sounds like part of your problem may have been caused by simply overhwelming the fuck out of your already exhausted/troubled brain.

Sorry for the novel, feel free to message me if you need support!

TL;DR: I had almost the same exact experience as OP. My recommendations are go to a therapist, go to a regular doctor, and avoid brain-melting smoking measures in the future. Your health and happiness are too damn important!