Itching In The Vaginal Opening. Lump Getting Bigger. Reason?

Hi, for the last week or so i ve had mild itching just outside the vaginal opening, but wasn t too bad. But then after itching it a bit too much i noticed one side had swelled up into a lump where i had been itching. I stopped itching it and applied an anitseptic cream to the area and a few hours later it has now gone down to normal size but something still doesn t feel right down there. I haven t had sex in a month, or changed any wash powder etc. There are no other symptoms, my discharge is normal.