ELI5 Why is it that people can still feel pain at all after receiving an electric shock, but people with aphantasia/phantasia-like disorder/whatever can not?

It can be a pain/relief thing, or it can be a weird, intermittent, "waking up" feeling? Like when you're really scared, you're freaking out about being attacked, and suddenly the room is full of snakes and monsters, and the noises don't seem to matter. But when you're not really scared and don't have any pain/ting, your body starts to panic/react, but then after a while the hallucinations just don't get it, so like, I'm fine, but I'm freaking out, and it's just that after I've experienced fear, I just go "aha I feel fine" and when I go back to a normal room, it's like I was a completely different person in there, it doesn't make sense that after a while you'd feel like you were completely different person.