Could be a type of migraine, there are so many. I suffer from 3 diff types myself. The doc dx is 'complex migraines'.
If you can, try to find a diagnostic specialist. They are hard to find, mostly in large cities and major hospitals. Teaching hospitals at that.
here is a link www.relieve-migraine-headache.com/diet-headache-migraine.html
for a headache diet.
I would like to point out that any food dyes especially red and yellow can cause a lot of symptoms for people, doctors do not agree on the whole, but I am one person of proof.
I hope your mother feels better soon. Please let us know if you find any help.