do you take prescription meds, supplements, drink or use drugs? I think the spasms could last a long time w/ a vibe but do you have like the whole intense sensation of complete ecstasy? I'm not really sure if your brain chemistry can be in flux for that long without some level of stimulation to your nervous system. It would chemically be pretty similar to your brain being high (you might have like a super unique nervous system but its more likely you're brain chemistry is being influenced by something unrelated to arousal yet is allowing you to have these long intense experiences). You didn't mention anything but do you ever feel off, sad or down after or within a few hrs of the orgasm (or otherwise)?
i've had long orgasms when using a vibe that def felt like one orgasm but after a while my body psychically might still be "turning out" but that rush is gone or at least faded significantly so i don't really consider it really one orgasm after the initial "high" fades. I think w/ vibes its more like multi orgasms that kinda feel like one big long orgasm