Why Am I Referred To Neurologist For Headache?

I had a headache for weeks but cannot get an answer. I was treated for migraine headaches, sinutitis and trigeminal uralgia. I got a CT scan and everything looks fine according to the doctor. He ordered it to check the sphenoid sinuses and the brain. I still have the headache but the last doctor referred me to a neurologist. That appointment is on the 27th of the month. Please tell me what could be wrong?