Why do not hospital give patients with mild head injury some info on post concussion syndrome?

I had a head injury and had a CT scan done at the hospital. Everything looked normal so I was released with info on some dangerous signs to look for, and told to follow up with my doctor in two weeks.

The next day I felt awful, I did not know what was happening. By the third day I searched the net for answers.

I had headaches for seven weeks. I am still recovering.
I really feel for those with more serious injury.