Brief Answer: Not serious. Detailed Answer: Hi, Thank you for using Healthcare Magic. You do not need to be concerned. Although your injury was, no doubt painful, the swelling will go away. When you initially injured your buttock there would have been some bleeding into the muscle due to the trauma. This will have collected and formed a hematoma which is a collection of blood. The hematoma will then have become hardened as it resolves. This is what you are feeling as a hard lump. I can reassure you that this will eventually disappear but it may take over a week depending on the size. In the meantime, it may be tender. You may wish to take pain-killers and paracetamol and ibuprofen would be my suggestion. I hope this is of help. If you have any further questions, please do not hesitate to contact me. Regards, Dr K A Pottinger, MBChB FRCA

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