Hi,
I suspect that CD is correct about how a tribunal is likely to view headaches.
However, in relation to conditions such as ME/CFS, these are usually assessed by the DWP and tribunals using both the physical and mental health tests on the grounds that ME/CFS is a physical health condition which also affects mental functioning, because of such things as extreme fatigue making concentration very poor.
In the same way, although a headache is probably a physical health condition, its primary disabling effects are on mental function and so I would argue that it should be assessed on both mental and physical health grounds.
There's certainly nothing to stop you putting forward this argument along with arguing reg 29 and, should your appeal be unsuccessful, you may have grounds to appeal to the upper tribunal.
Though it would be worth doing a search to see if there have already been any UT decisions in relation to whether headaches are physical or mental health conditions or both.
Good luck, do let us know how it goes,
Steve
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
