Hello, * As per my surgical experience, the painful boil on the testicle do indicate underlying inflammatory response of the body to certain infection issue. * The primary pathology may be bacterial infection with staph aureus or other bugs in the previously existing sebaceous cyst or folliculitis in sweat glands. * Depending upon the clinical presentation, it does have various modes of management as: - if small, developing - trial therapy of oral antibiotics, sterile dressing - if large enough or not responding to above therapy an incision and drainage proceudre as day care surgery may prove curative with excellent results. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr. Bhagyesh V. Patel