<s>[INST] hello I have a hard lump under the skin on MY buttocks with cellulitis redness and some pain. when taking doxycycline, the lump goes down pain goes  away. I did get a rocephin injection over a Year ago in that spot. thats when all this began. pls help im starting to worry [/INST] Hi, I had gone through your question and understand your concerns. At this area it may indicate several issues and most common are colonial cyst or perianal abscesses. These are inflammatory processes in sacral and perianal area usually manifested with pain, redness, swelling, fever and pus discharge. Cellulitis is less common and may be present in sacral area as well. This is mostly caused by beta hemolytic streptococcus, and it necessitates antibiotic treatment with augmenting, or combination of Capitol+ metronidazole. You should also, apply cold compresses, take nonsteroid painkillers such as ibuprofen 400 mg and rest. If there is no improvement within 2 days, you should see doctor and have intravenous antibiotics. Hope this answers your question. If you have additional questions or follow-up questions then please do not hesitate in writing to us. I will be happy to answer your questions. Wishing you good health. </s>