Hi, I understand your concern and I ll try to help you. According to the description of the injury you reported there is a subgaleal hematoma that arose after the trauma to the back of your head. An action to relieve the pain is to make cold compresses on site and you need to stay alert to the warning signs. The warning signals after a head injury are loss of consciousness after the trauma, feeling of nausea, episodes of vomiting, dizziness, progressive worsening of the head pain, altered behavior, confusion, excessive sleepiness. It is important that you and your family be alert to the appearance of any of these signs and if they appear, you must immediately seek emergency care. Emergency care should look for fractures and intracranial bleeding as subdural hematoma, subarachnoid hemorrhage, epidural hematoma, and even cerebral concussion. Therefore, although no alarm signals currently be under surveillance and search a hospital in case of appearance of any of these warning signs above. Hope I have answered your question. If you have any further questions I will be happy to help you. Wish you good health.