If you stub your toe, you can't prove to anyone else that it hurts. Scans showing various things like nerves firing won't prove it. Redness, swelling bruising etc. - none of these prove your inner experience of pain. For all I know you might be making it up, even though I tend to believe it because of a similar experience. Same is true for any experience. One man sees gray where I see green if they're color blind. Which is the true color? I can't say "green is true" just because most people see it and a small proportion of people see something else. A chameleon's eyes apparently have a view of the world which is....hard to describe, but it's not like what we register with two eyes. So the "show me the proof" angle isn't an approach that will be useful, imo. Experience is personal and not possible to share other than through words.
