2 ms·how would he know if he had a concussion and internal bruising if he hadn't been to a doctor?by masukomi 10y agohow would he know if he had a concussion and internal bruising if he hadn't been to a doctor?mrits 10y agoThe same way the rest of us self-diagnose? WebMD at 2 A.Mwayn3 10y agoIf your car gets hit in the side and you knock yourself out on the back of a seat, figuring out you've got a concussion doesn't require expert problem solving skills.