Forehead & scalp has a rich supply of blood, and injury to these areas results in bleeding under the skin. When the bleeding is restricted to one area, it causes bruising and swelling, and it is referred to as hematoma in medical term. Because of rich blood supply, even minor injury can cause large hematoma. Hematomas tend to resolve over time. Occasionally, blow to the head may be severe enough to cause bleeding in the brain. This type of bleeding can cause an intracranial hematoma, a serious condition that puts pressure on the brain. Seek emergency medical attention if you experiences: unconsciousness, confusion or disorientation, vomiting, mood changes, memory loss, and persistent headache after head injury. Advice 1. Apply ice pack locally. Do not apply pressure as it will hinder natural process of healing 2. Take rest for few days 3. You can purchase oral over the counter pain killer pain killer if pain is unbearable. If you can tolerate pain then avoid oral pain killer 4. If your condition is worsening then go to hospital for further investigation by CT scan/MRI and treatment Thanks!!