The above is good and informative suggestion.Follow it.
Some people have above average sebaceous glands on their genitals, to say they are above average means they are more numerous, larger or higher producing then that of the average person. All Mammals have sebaceous glands and on humans the genital sebaceous glands for men are on their penis near the base and on the under shaft near the glans (head); and for women they are on their labia minora. The purpose of the sebaceous gland is to secret a fluid called sebum that moisturizes, lubricates and protects hair follicles, sensitive skin and external mucus membranes. Sebum itself has no odor and quickly degrades, so as it is easily broken-down it is consumed by bacteria which can produce an odor. You may have above average sebaceous glands resulting in a high production of sebum which could possibly be allowing for bacteria to grow which would produce an unpleasant/foul odor. My recommendation would be to wash the area more often; at least twice a day and be sure to dry thoroughly before applying any powder and shower after any heavy period of sweating. Also be sure to use the highest quality after shower powder or a high grade baby powder, many talcum powders contain silica; which is abrasive to the skin creating micro-scratches that are an excellent place for bacteria or fungus to colonize.