Hello, I have a large hard mass inside my right buttocks . I had a fever , and my doctor opened it to drain it it as I had a fistula in the same area in the pst. She told me little to know fluid cam out and that the tissue was irregular, so she took a biopsy for testing. Along with this I had a low grade fever and general flu like symptoms, she put me on antibiotics to fight the infection. Fever is gone but mass is not getting smaller. I am on my fourth day of antibiotics. What might the issue be and how concerned should i be ?