back massage are not supposed to tickle. Most areas that have knots in the back are the shoulder upper area by the neck. You light fist.. like if you were to tuck your fingers in but not your thumb.. like animal paws... and roll your knucks on his back..,. or you can lightly grip with your fingers and apply pressure using your palms.. and slowly inch your way across his whole upper back area.
If you are frisky, not too young, and not too religious.. the area above the buttox makes for a nice massage!