I am drinking lower caffeine coffee at brekky time.
No espresso shot in the am – green tea instead.
I am requiring a little “pick me up” of coke zero in the arvo.
And by 4pm……sore head.
The last 2 nights I have flopped into bed with a headache and slept for 2 hours.
In the arvo, my brain is mush. So it is either the gastro-oesophageal junction or brain that suffers.
It is like coming off crack.
Demons, dancing, doctorates, debauchery. 
Gosh I know exactly how you feel. It’s so frustrating going through the withdrawals. However then you’re body does the reverse thing if you end up going back on it again. Since being on this diet I’ve noticed that whenever I eat sugar I get a headache and really groggy. So the withdrawals are eventually worth it!