What Causes Itchy Redness In Vagina And Thighs?

good day. would like to ask advice on what to apply or any medicine i could take regarding my red itchiness near my vagina lips and near thigh areas? i noticed it occur when i wear tight jeans and undies. when i walk it burn/sore. my legs are bigger than usual. i even tried not to wear undy when i sleep at nite. but lately, it occur whether or not i wear tight jeans and undies. thanks in advance for your assistance.