What Could Lump On Vagina Indicate?

Hi, I am 41 years old and on HRT due to early menopause. About 2 weeks ago I felt a funny feeling in my bottom (probably a slight pain when I would be cleaning myself after going to the toilet). I looked a few days later and came across a pea size lump on the right side of my inner lips (about the middle external side). Couldn t say it was painful. I am a worrier so I made an appointment with the doctor - not my own doctor, a junior reg. She examined me and took an internal swab which came back OK and she said it looked healthy. I was given a course of antibiotics which has had NO change on the lump whatsoever. She didn t think it was serious by the look of it. At the same time on my right labia majoria I had like a numbness pain it isn t totally away but nearly. Being a worrier I am very concerned could this be cancerous or something serious? Can you help me.