A pain, tenderness (hurting or squeezing) and slight increase in size point to an infection. This may need a course of antibiotic. One of the possibility is sebaceous cyst, which is quite common in this area. Sebaceous cyst need a small surgical procedure to remove it (office procedure). Meanwhile you can do following;
1) Ibuprofen (Motrin or Advil)
2) Warm compresses
3) Application of Betadine (povidone iodine); this is available at health stores without prescription. This is antibacterial solution which will control the infection.
Please feel free for your follow up questions.
Many times the local antibacterial do take care and completely eradicate the infection. But yes, there is a chance that you may need to go to a doctor for the small procedure.
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