Well this thread at least brought me to this interesting philosophical concept: https://en.wikipedia.org/wiki/Private_language_argument

By analogy, it does not matter that one cannot experience another's subjective sensations. Unless talk of such subjective experience is learned through public experience the actual content is irrelevant; all we can discuss is what is available in our public language.

Wittgenstein suggests that the case of pains is not really amenable to the uses philosophers would make of it. "That is to say: if we construe the grammar of the expression of sensation on the model of 'object and designation', the object drops out of consideration as irrelevant."