Consider whether we should define electrons to be "positive" or "negative": there isn't any fact of the matter, it's merely a convention. But it doesn't seem like experiencing pain works this way: pain feels a particular way. If pain is just a mathematical entity, there shouldn't be any particular way that it feels, since it's just a symbol.

Maybe we're deeply wrong about our intuitions, and actually no conscious experience is happening in the brain at all, despite the brain having an incorrect model about itself which predicts this (and causes it to make utterances claiming that it has experiences). That's the school of thought known as eliminitivism. Under this view, all suffering is a myth, in the same way that luckiness and angels are.