Holy wow, I didn't realize things had deteriorated so much.
x2 on the above comments by nw and michelle.
It was my understanding that CRC rarely crosses the blood-brain barrier.
But it DOES get into bones, including the soft blood-carrying inner tissue of the skull; since you've had blood-marrow issues (which produces WBC's), perhaps the brainiacs are considering that. I dunno.
I have one dime-sized tumor 'lens' in the skull at my right temple, but it's never grown nor been a problem.
Do you have a pain-mangement doc on the team?
Occasional 7-8 pain sessions do not seem like something you should just expect to tolerate.
Have you ever had headache issues during your younger years?
Headaches can also be a sudden-onset system of dehydration/heat-stroke; KEEP HYDRATED, even to the point of excessive urination (while watching electrolytes).
Different colors/quality of light can also do strange things: Sunlight vs. incandescent vs new-fangled CFL's vs computer screens; the vision nerves are direct conduits to the brain.
Yet the olfactory nerves carry much info and affect different centers, especially long-term memory; any new odors in the house or neighborhood that could trigger something?
Just some ramblings of an old architect who tried not to pain his clients with ugly buildings.
If you have access to medical pot, it is wonderful for IMMEDIATE relief of moderate pain, since nothing gets to the brain more quickly than an inhaled substance.
Forget its history of negative connotations; it has been used throughout the world for millenia for effective pain relief, for good reason: It works, and it's relatively benign.
I'm glad you're acknowledging your body's new limitations, I think that will serve you well.
Listen to your body, and hang in there.
HTH, Rick