your head/brain is not as fragile as that. you are not going to die. your anxious thinking is playing tricks on you..
an example--- my eldest is disabled. part of that are seizures. one day she had a seizure on the stairs; she fell down the stairs and hit her head on the molding on the stairs. it cut her scalp open. she needed 7 staples to close the wound. With such a HARD fall and knock to the head, a ctscan was done. and the scan was normal. You didn't hit your head anywhere near as hard as she did.