Yikes. My best wishes to you, Kate.
As for the aneurysm: The sister of a friend of mine has one, it is not possible to remove it, and if it should burst, she could die at any given time. So if it is possible for you to have it removed, I would strongly advise you to get that done.

As for the "only in your head": Doctors can be such idiots. I used to joke about migraine ladies until I had one very severe attack. I think it was due to traumatic reasons, as my 8 month old nephew had just died of sudden infant´s death, and I never had another migraine headache ever since...
However - the pain grew constantly worse for the time of a week, I kept crying and womiting, could not eat, could not sleep for more than 15 minutes in a row, no painkillers helped, and I could not even locate the pain, for whenever I touched the hurting place, the pain jumped to another place, usually the exact opposite side of the head.
"It is only in your head" is about the LAST thing you want to hear in such a situation...

Yes, I got a CT, and yes, it feels like a coffin *shudders*.

Again, all my best wishes, and a speedy recovery in any way that is possible...

Hugs (yea yea I know).
Arria