My friend's cousin

Some days ago one of my colleagues told us a very sad story. It's written below:
She had a 38 year old cousin. On Tuesday when he was passing the street suddenly a car hit him, he felt into the ground and his head was injured. He stood up and checked himself, there weren't any serious problem, so he asked the driver to fetch him home, thanked him and said goodbye. After one hour he felt some pain in his stomach and head. It turned worse and worse until he died!!!
Actually the accident had caused him to have some internal bloodshed and at that moment he didn't understood anything otherwise maybe if he had gone to hospital he would be alive.
As one of my friends said how lucky the driver was, not because he wasn't there to pay for his injuries and death but because he never understands that he has killed someone unwontedly.
It was really sad, God bless him but we should always go for a complete check up after any kind of accident inorder to prevent such things.