Welcome to health care magic. 1.Most possible cause could be infective aetiology of the hair follicle with collection of pus within. 2.In this case the treatment would be a course of antibiotics that would help. 3.If the lump is big and not reacting on antibiotics then a small incision and drainage followed by the antibiotic course is treatment of choice. 4.Mean while as a remedy do not press or scratch the lump, as interference with the lump will delay in healing process and complicate. 5.Mean while until it heals do not shave the region, instead use trimmer to remove hair, as shaving will again irritate the lump. Maintaing local hygiene and clean with antiseptic liquid, use soft clothing. That will help. Good luck. Hope i have answered your query. Any thing to ask do not hesitate. Thank you.