Hey Atama,

Your problem may be an allergy... compounded by a low vitamin D3 status.  You can see your PCP or neurologist for a lab test of your serum 25(OH)D.  This is the first metabolite of vitamin D3 that's used to measure its status.

Allergic reactions to a wide variety of allergens, mostly pollen this time of year, create a flood of histamine throughout your body.  When histamines reach the brain and in particular, the hypothalamus and trigeminal ganglia, they trigger the release of calcitonin gene-related peptide (CGRP), Substance P (SP) and likely other pro-inflammatory agents.   This could easily explain why some CH preventatives that have worked previously, stop working...

There are recent studies indicating the serum concentration of CGRP is elevated during the pain phase of cluster headache (CH) and low during the pain free periods between CH.  Many of us have found taking a first-generation anti-histamine like Benadryl (Diphenhydramine HCL) helps CH preventatives work more effectively. 

The likely mechanism of action involves Diphenhydramine passing through the blood brain barrier to block H1 histamine receptors on neurons within the hypothalamus and trigeminal ganglia. 

Once the H1 histamine receptors are blocked, neurons stop releasing CGRP and this enables CH preventatives like verapamil to start working more effectively.  Second- and third-generation (non-drowsy) antihistamines cannot pass through the blood brain barrier as rapidly so are less effective if an allergic reaction is causing problems with your CH.

Many of us have found Children's Allergy Medicine, Liquid Benadryl (Diphenhydramine HCL) can work effectively in cases like this at a dose as low as 12.5 mg (5 mL in the measuring cap) in the morning and another 12.5 mg in the evening. 

Many allergic reactions are sub-clinical, i.e., no outward or obvious symptoms but they're still there triggering the release of histamine.  Accordingly, trying the Children's Liquid Benadryl (Diphenhydramine HCL) may be worth a try.  Just be careful if you need to drive as even low doses of Benadyl can create drowsiness. If you do need to drive during the day, wait until you're home for the day to start the two doses of Benadryl.

I've sent you some additional information in a PM.

Take care and please keep us posted.

V/R, Batch