The point being, that when you are on fire, you feel pain as a consequence of your pain receptors in your body firing in response to tissue damage. Depending on circumstances, You can also feel pain without these receptors firing, and you can also feel no or little pain when these receptors are firing a lot. You can say that the pain originates either from the receptors or from something internally in the brain. Naively you might describe the first type as 'real' and the second as 'imaginary', which is of scant use to downright dismissive of the person actually experiencing said pain.