Can you elaborate on the problem? Not sure how to help otherwise.
How long have you been stepping?
Does he live with you full time or is he just visiting?
Did something specific happen/when did you notice your discomfort?
Are other kids involved?
What did you say to DH and how did he respond?
Are you home all day or out of the home mostly?
My default answer is though, that this is primarily an issue between you and DH, not an issue between you and SS. You and the dad need to work together.