His symptoms sound like they could be due to a number of things possibly related to the accident, but it's important for his doctors to know whether or not he had any head injury
. If he lost consciousness briefly and
was told he had a slight concussion
, then he could have post-concussive syndrome characterized by headaches, nausea, neck discomfort, and dizziness among other symtpoms such as restlesness, nervouness, anxiety, and fatigue.