Sometimes our body parts like genitals face hands and ect itch for seconds having no health problem. why does this happen?

Body itching : On face and hands could be dry skin, irritating lotions or soaps or fragrances, bites, eczema ( though that would happen in a more frequent fashion and usually there is a rash). In the genital area, could be same dry skin, douches, eczema ( would see skin changes) or infection like yeast , bacterial vaginosis or very rarely cancer or scabies ( but would see marks). f/u /w/ MD/ dermatology,