hi i think it is a furuncle
or abcess not cyst. it may be due to excess moisture in that area or uncleanliness in that area.it is just a infection of the hair follicle and subcutaneous tissue
.u can the all the features of inflammation around it.first try antibiotic twice daily and anti inflammatory agent like flexon
twice daily and application of t-bact ointment over the lesion.if still not cured go for a surgeon for incission and drainage
of the lesion.