I have. I have no evidence that either pain killers or placebos work in any sort of medical sense; I have clear evidence that swallowing a pill causes me to relax, resulting in a immediate reduction in pain.

Do you take the pills with water, and if so, have you tried just drinking the water? I find that water reduces a great many pains for me, including headaches, muscle cramps, and digestive difficulties, so it wouldn't surprise me in the least if the effects you're observing are from water taken with both the pain killer and placebo.