One thing's for sure. When I say "please stop", I mean it! It's EXTREMELY uncomfortable for me, and does closely resembles pain.
And I'm the one who's suppose to have the desensitized glans here!
The rule is if your guy says to stop, please stop. Give him at least a couple of minutes for the hypersensitivity to subside before attempting to stimulate him again. He really does need a break.