Hello and welcome to Healthcaremagic. I am Dr Asad Sami.I have read your question and i can understand your concerns.I will be answering you. What is your age.?? What is your profession.??you have to sit for long hours..?? Any history of diabetes or other Iimmunosuppressant conditions.?? Any history of chronic diseases such as tuberculosis or inflammatory bowel disease..?? According to the information you presented you probably have a Pilonidal abscess or Pilonidal sinus. If I were treating you in my clinic i would have examined that area to look for fluctuation of fluid underneath.this is positive in abscess.for abscess i would have aspirated the pus and I would have sent it for culture and sensitivity.I would have prescribed a trial of antibiotic such as ampicillin plus flucloxacillin 500mg four times day.It usually subsides with antibiotics and if doesnot subside then it will need incision and drainage. Pilonidal sinus is another possibility.it is a branching tract beneath the skin lined by epithelium which has opening outside the skin.Its treatment is surgical exicision of the tract by karydakis procedure. I would suggest you to meet a general surgeon.In the mean time remain calm and keep that area clean with hydrogen peroxide or pyodine. Thanks. Hope the answer is helpful. Feel free to ask further questions. Regards.Dr Asad sami