This could be a cyst which could turn septic. I recently had a lump on my butt that I thought was a boil. After being untreated for a week I became very ill and ended up in the ICU unit with blood poisioning. To make matters worse I am Diabetic which lead to Renal failure and Kidney function interruption. My hospital stay lasted 17 days, 13 of which was in ICU. My blood pressure dropped to 60/40...I could have died! P L E A S E see a doctor ASAP if you haven't done so already.