Hi Claire,
I haven't heard of the clump part of 'cluster clump headaches' before - I'm assuming the neuro was referring to what we just call cluster headaches, which I'll just be abbreviating to "CH".
There are those who believe CH can't be caused by an accident and recent theories about their cause include a defective hypothalamus.
Personally I've seen too many reports of CH either induced or dramatically worsened by head trauma, and I think the writing is plainly on the wall that that sort of injury can induce it.
It's a seriously horrific thing to be saddled with alright - or it
used to be. That's my perspective at least because as a 30 + year CH'er I've gained significant relief, as have many others, through info and advice found at this site and at clusterbusters.com.
You and/or your dad need to make these message boards your mecca and the info here your CH bible. Just entrusting a treatment plan to a doctor without question tends to be a recipe for disaster!
Some brief rundown of important CH points:
Never trust any neuro at all except for a headache specialist. Garden variety neuros are all to often ill informed about CH.
High flow 100% O2 (which is more effective than how doctors usually prescribe it) as outlined in the left side
oxygen info link is a super popular abortive around here since it is so effective and non toxic.
Others will give you the rundown on drugs. Personally after being on pretty much all of them, including heavy drug cocktails, I'm currently favoring these two non prescription approaches for prevention:
The relatively new vitamin D3 based regimen which has some folks here reporting going into remission, and appears to just be good for the health regardless: Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

The very powerful clusterbusters approach, which has been known to the online community for years now, and has enabled many CH'ers to go into remission:
Newsweek article on Clusterbusters - Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

Video talk on the subject by a CH'er: Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

Sorry that your dad had this terrible accident, but CH
can be treated effectively in most cases!