Hi thanks for your question.
The bump which you have near your vaginal opening could be most probably a bartholin cyst
.Bartholin glands are normally present in vagina and produce screations for vaginal lubrication
.Block in bartholin gland duct or infection of bartholin gland produces bartholin cyst.The other possible could be a boil (infection of hair follicle).There is nothing to worry,get youself examined by a gynaecologist to determine what exactly this bump is.
Hope this answers your question.