Hello I appreciate your concern This could be a infected sebaceous cyst or Lymphadenitis (infection of lymph glands) If you can upload me a photograph or complete medical history I will be able to guide you better like Since how long it has been there? Is it of the same size from the day you have seen it first time? In my opinion you should consult a general surgeon for examination and excision of the cyst once it gets clear of the infection Maintain good hygiene Please don t manipulate much with this You should wash it with antiseptic solution and keep it moist Hope this addresses your query Thanks for using our services wish you good health