If any system varies from its expected performance, I feel it as an illness or slight pain.

It helped cover the slight pain that was developing in his stomach.

He felt a slight pain in the wrist of his right arm.

"I am no babe who cries out at the slightest pain."

It was a slight pain to him to be brought to.

All they felt was the sting of a slight pain.

The slight pain blended into his pleasure, driving him higher.

I am sorry now to be the author of the slightest pain to you.

You probably didn't notice the slight pain what with everything else.