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1.The history and location suggest the possible cause could be hair follicular infection with collection.
2.Next possible cause could be subcutaneous infective
abscess / collection.
3.In the both cases in small and not compacted state a course of antibiotics will help in treatment.
4.In case of complicated state a small
incision and drainage will be needed - but the size you have mentioned does not suggest that - however need to examine.
5.Finally till you get treated as a remedy - do not squeeze, press, scratch the lumps ( in that way you will complicate ), maintain local hygiene, clean with antiseptic liquid, avoid clothing that irritates that area - soft clothing suggested. Good luck.
Hope i have answered your query,
any thing to ask do not hesitate to ask.
http://doctor.healthcaremagic.com/doctors/dr-ganesh/62888