sounds like you have photosensitive epilepsy wich react on very low frequenzies if fireworks can trigger it.. :S

my personal frequenz is Tekken1 on a playstation1 and the spectre is pretty small cause tekken is the only trigger i´ve had.
But anyway, yes, cannabis DO enhance the triggereffect but for me too, but the seizure comes much more slow so i get a warning if i experience one tough its allmost 8 years ago since i had my last(been smoking for 7½..).

im not on any sort of medicine, i slam bong on a daily basis..