Nurses preferably but any answers welcome :)?

I have a lump on my labia majora it was small and painless and had a whitish head but no that is gone and its become a littl bigger and is the same pinky colour of my skin down there. It feels fluidy and spongy to the touch. I thought i had a sebaceous cyst but now im not so sure. Does anyone know what it could be? Btw im 15 years old and not ually active