What Does A Split On Labia Minora Means?

I just noticed that the edge of the top of my labia minora(?) has this weird, s shaped split in it such that the two halves fit perfectly together. Almost like a thin, ovular ying yang. On the upper side, directly next to the split there is a pea sized whiteish lump. It is not recurring, red, nor bleeding. I have no idea what it is but it stings a little.