Red swelling in vulva region. By doctor.

Hello doctor I my daughter is have a red lump filled with pus painful it is growing in size. It doesn't attach with underlying skin...This type of condition has occurred before on different area near vulva only  the swelling goes away after the pus get discharge within a week after taking antibiotics and some ointment application as prescribed by doctor... My concern is why does it keeps on reoccurring at different places and after it subside it leaves small lump behind she has two of it before and this swelling generally happens between month of feb and March mostly for past 2 years. What can be the cause and line of treatment and my daughter is very peculiar about her hygiene she does clean that area as suggested by doctor.