how would you consider a pain is a pain...?

The degree of pain in someone is unknown to another. My pain is invariably no pain at all to others. Vice versa. But there is one category of pain that can make the difference, that is, your pain is my pain. I can feel it and I can sense it. It is being seen as a bond between two persons.Wonder how many out there are in serious pain for something but in actual fact can't be felt by others? Allahuakbar.