Anything *can* happen as far as odd allergies. Out of the blue I developed an allergy to a common OTC painkiller I’d used for years when I needed, fortunately not severe enough to warrant not taking it but very annoying.
if all of a sudden I’m itchy and overly sensitive from a couple ibuprofen, why couldn’t someone be flat out allergic to pot? or LSD?
I suppose it's possible. I've had allergies (pollen, dust, grasses, animals, molds, etc.) since I was a kid in the 1950's, and over the years they have changed, come and gone, and either responded to or resisted various treatments.
Frankly the single most important factor in my case is stress, both physical and psychological. If I'm in good physical shape and healthy attitude, and not under a lot of stress, I hardly notice them. When I'm stressed-out about work or personal stuff, or my attitude is shot, they flare up.
So it's possible the bride in the story is allergic to acid. But given the extremely low incidence of such reports, when used by hundreds of thousands of people over many decades, I have to think it's unlikely, and that something else caused her bad trip. Assuming it was a bad trip -- the story isn't clear, and she might have had an argument with her groom, or just done something stupid and injurious while tripping. That happens a lot more often than spontaneous bad trips, per se. We just don't know what really happened.