Welcome to NeuroTalk:

Can you explain this corneal scan for us? I am only finding corneal scanning being done on animals so far.

I did find this very new study, from 2015, but the study group is small:
http://journals.lww.com/corneajrnl/A...orneal.22.aspx

I cannot recall anyone else coming here who had this corneal scan yet.

When you had your colonoscopy done, did you get spinal anesthesia? Spinals can sometimes cause headaches or leaks.
But a leak is less likely is you did not have a spinal.

A leak can come anytime though, but those are not very common.

Patients with neuropathies can be low in magnesium. This is very common in just the general population. Magnesium therapies have been used in treating migraines successfully, too.
So you could take a good supplement (not oxide forms), like SlowMag twice a day. This is about 1/2 the RDA and may move you up if you are mildly low due to poor food choices.

Here is the SlowMag website, it is OTC:
http://www.slowmag.com/
If you feel better on this (should be a few days only to see improvements) you could cancel the invasive myelogram.