I was thinking maybe a FLIR thermal imaging camera to record heat variations on the body. If an area shows temperature increases, it would suggest a real phenomenon. I guess we'll see tests like this in the future as he seems very open to being tested.
Depending on the cause of the pain, FLORIDA may not show much. Inflammation is if memory serves, often accompanied by increased blood flow, and thus the area is warmer than the surrounding tissue. Though, a notable change in temperature during the process would be indicative of something happening at least...
Edit: ... FLIR, not Florida... Bloody autocorrect...