Occipital neuralgia?

I had had these crushing, ice pick headaches for the last month. Three times, so not consistent. The pain is so Severe (think Stranger things/Disrupter Sonic) feels like intense stabbing and leaves me completely useless at moments. (had to stop meetings, driving etc). How do I get this connected to my airborne accident or prove that it's secondary to one of my original issues? I think proving I have a crushing headache is hard enough. Is there a way to increase my service connection? The last few months I am having major health issues (I am 42) and in and out of the hospital and non-va doctors due to where I live. Any help with documentation procedures, what I need, scans?