It seems that you are having candidal balanoposthitis
It is fungal infection
, caused by candida albicans.
Sexual intercourse, Excessive washing with water,soap,perspiration...etc may precipitate CBP.
Take anti fungal tablet for few weeks.
Apply anti fungal cream.
Improve immunity with immunobusters.
Take sitz bath in dettol
Avoid stress and worries.
Give anti fugal therapy to your partner.
Still, you consult dermatologist
I hope you got my answer.
Ilyas Patel MD