A large hard bump on the buttock with intense pain may be caused by internal heat and fire, or a subcutaneous cyst caused by a viral infection. If this is the case, it can be treated by taking Niuhuang Detoxification Pills or Amoxicillin capsules. It may also be caused by bacterial infection. It is recommended that local disinfection with iodophor and treatment with erythromycin cream or Bactrim can be applied. However, the specific cause should be analyzed. If you find a lump on your buttocks and have pain, you should go to the hospital promptly and have a comprehensive whole body examination if necessary. Only when the specific cause of the hard pack is clearly identified can reasonable and effective treatment be targeted. Avoid spicy and stimulating foods and eat more fresh fruits and vegetables.