Probably a big hematoma has formed there due to bleeding under skin because of rich blood supply of forehead. Hematoma tends 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. Advice 1. Apply ice pack locally. Do not apply pressure as it will hinder natural process of healing 2. Apply Thrombophobe gel (heparing gel) locally every 4 hours for 10 days 3. Take rest for few days 4. Seek emergency medical help if your friend experiences: unconsciousness, confusion or disorientation, vomiting, mood changes, memory loss, and persistent headache. I hope this information will help you. I will be happy if you ask another question Thanks