The only way to diagnose a head trauma is thorugh diagnostic testing ie: xray, cat Scan, MRI, Each test will show something different such as: fractures, contusions, concussions, clots, etc.
For example: I have had multiple concussions.Concussions are often discounted as not having long term effects but to the contrary the effects can be longterm if not life long and impact things in such a subtle way that the symptom might easily be construed as another problem.
This type of injury is the exact thing that does affect the frontal lobe. A learning disability early on could have been the result of an injury early in life that went unnnoticed/undiagnosed. It is a good idea to try and remember your medical and physical history as well as your families in order to determine what is the cause vs what is the effect. I am going through this myself right now and I understand it is frustrating, but the process begins with you writing down your background, symptoms and concerns.
Your primary care physician can refer you for whatever test s/he thinks is appropriate. Unless you have enough to do the cash and carry method (pay everything yourself) you have to start this way. Insurance wont pay for a specialist without concrete proof you need one. To get to a specialist, you need to be properly diagnosed through one of those test I mentioned. Those test can be ordered by your primary care physician who will refer you for a diagnostic test -and determine which is best for you-based on your symptoms.