Itch in genitals for around a month ?

I have an itchy area all over my vagina and the anus sometimes. I have had a swab test with all negative results abd seen three doctors but they say it might just be from stress etc. It is on and off and is really irritating me. I asked about other things like herpes but seeing as I don't have the blisters the doctors said it doesn't sound like it. I am very worried, please help.