Is man merely a mistake of Gods? Or God merely a mistake of man? --- Nietzsche
Perhaps this is what lies at the root of much self-harm ie: self-cutting etc. A way of moving the pain from the inside to the outside.
Yes, if someone is oblivious to physical suffering, then the mental suffering is that much more exaggerated. Perhaps it is similar to what happens when someone becomes blind or deaf and their other senses are heightened.