I Have A Small Pea Sized Lump On My Labia

I have a small pea sized lump on my labia minora next to my clitoris. It is itchy and uncomfortable. I am not currently sexually active, and haven't been for about 3 months. I also just started my period 2 days ago. It seems as if it is getting bigger. It doesn't hurt really. More itchy and irritating. Is this a cyst or something more serious?