Suggest Treatment For Red Itchy Bumps On Genitals Of Child

My 5 yr old son has red itchy bumps some have a white puss head on the shaft of his penis and on his genitals. On his legs there are smaller pink bumps that do not bother him. What could it be and how do I get rid of it? We have not changed soaps, clothes, or detergent. He has had it for about 3 - 4 weeks. I ve tried powder and creams.