Hello. Thank you for contacting HCM. I have gone through your question and your son appears to be suffering from an infected pilonidal sinus. Pilonidal Sinus is basically a cavity or channel which is caused growth in that area, friction due to tight clothing, hormonal changes or infection....it can be a combination of all these. If it is caught early on, with mild infection a course of antibiotics is sufficient to treat it. If the infection is severe and has lead to abscess formation it may require drainage of pus and blood from the abscess along with cleaning that area from hair and debris. The wound is then packed with sterile dressing and within a period of three to four weeks it heals from outside naturally closing any sinus opening. I would recommend your son consults his local physician for detailed clinical evaluation and further management accordingly. I hope this answers your question. Please feel free to contact HCM again if you have any concerns. Wishing your son good health.