My son had a head injury while drinking with friends, because he was so drunk, he felt out of a friend's truck...I didn't even know until recently he told me...this happended like 7 years ago and he was fine after his injury, he didn't even go to the Hospital or nothing...he just remembered having a lot of pain...3 years ago he was diagnosed with schizophrenia...could it be part of his head injury? Is a CT Scan recommended after all this years?
A traumatic brain injury may increases the likelihood of developing a schizophrenia-type psychosis, but the evidence is neither strong nor consistent. However, your description goes nowhere near that of classic brain trauma. A delay of seven years may be a theoretical possibility in terms of risk factors, but I suspect it wouldn't come particularly high on the list. Of more interest would be family history, & perhaps lifestyle issues such as drugs and alcohol.
As to a CT scan - well I think that's something you would need to discuss with a medical professional.
Basic information about schizophrenia such as risk factors can be found on this site. Here's a link on understanding schizophrenia to get you started.