If this is definitely coming from the genital area she may have a problem with a genital fold that is trapping moisture. this leads to a low grade skin infection that has an odor. This condition may be corrected with a surgery that eliminates the genital fold. Any type of antiseptic soap can be used to treat the problem if surgery is not done. Betadine or chlorhexiderm shampoo would be quite effective. After washing, make sure the area is judiciously dry. Then you can apply a thin application of topical antibiotic ointment, such as bacitracin. depending on the severity of the fold, this may need to be done on a daily basis. Consult with your regular veterinarian regarding the possibility of surgery.