itchy around the side of my genital area everytime i have my meanstruation

i am 19 years ol, female. i have abnormal meanstruation sometimes. i have a light flow meanstruation a week before i have my real meastruation. it had happened view times. it began two years ago. I had gone to doctor to have scanned my womb, but he said no problem. the doctor just said it is because of stress, so it affect my meanstruation period.he gave me vitamins and hormone reparing. it stop for a year. after i entered my collage, it come again. i have the abnormal meanstruation for several times and everytime i have my meanstruation,it is itchy around the side of my genital area. not around the vagina. sometimes i have white mucus from my vagina and it smells bad. is it because of STD? i never do any sex with anyone. just kissing. is kissing can transmit STD? What is the cause, symptoms of STD and how to prevent it?

Please help....

I think you might have a yeast infection. if you go to the doctor, they can prescribe you some medication to help temporarily relieve itching and help to make the problem go away.