Thanks for writing here.
It seems you are having balanoposthitis
It can be due to infection,allergies.
Vaginal secretions can sometimes irritate the red part of penis causing balanoposthitis.
Treatment of both partners is essential.
You can apply a mild steroid like hydrocortisone
cream over affected area.
Avoid any soaps,detergents etc.
Avoid sexual act till compete cure.
You and your partner needs to take fluconazole
tablets for 2 to 3 weeks.It will be better if you take dermatologists opinion for this.
Hope this will solve your query.Take care.