Hey Vidster,
Uff da! CH is a bummer! Your consolation is you live in God's country, Tromsø, Norway. Unfortunately, you live so far North you don't get enough direct sunlight so you're likely vitamin D3 deficient and that deficiency contributes to the frequency, severity and duration of your CH...
I've never been that far North in Norway, but in 2009, I had the pleasure of driving from Oslo across the Telemark, down to Sauda, around the North end of Sandsfjorden and Sandeidfjorden, then out to the coast to Haugesund. As a kid who grew up in the Puget Sound area of Washington State near Paulsbo and Silverdale. Being around that much water and that many Norwegians felt like home...
I was a guest speaker at a Clustercompagniet conference there in Haugesund making a presentation of the use of an oxygen demand valve as a rapid and reliable CH abortive. I've moved on since then satisfied I'd found a very safe and effective method of oxygen therapy as a CH abortive to researching an equally safe and effective CH preventative.
In 2010 I finally developed what I call the anti-inflammatory regimen. It's a combination of off the shelf vitamins and minerals including 10,000 IU/day vitamin D3, 400 mg/day magnesium, 1200 mg/day Omega-3 fish oil, an adult 50+ mature multi and vitamin K2. This regimen has proven to be a very safe, effective, and inexpensive CH preventative. To download a copy, click on the following link at VitaminDWiki.
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You can visit my webpage there at VitaminDWiki at the following link. Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

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You can also go to a post I made here at CH.com titled Anti-Inflammatory Vitamin D3 Regimen and Survey in the Medications, Treatments and Therapy section... This thread has been viewed 75,626 times since I posted it on 16 December, 2011.
When you've downloaded a copy of this treatment protocol and decided to start it, take a copy to your PCP/GP or neurologist to discuss when you ask for labs of your serum 25(OH)D, calcium and PTH. The lab results for your serum 25(OH)D will confirm you're vitamin D3 deficient, i.e., less than 75 nmol/L (30 ng/mL). The other two labs will serve as baseline biomarkers to track your progress as you elevate your 25(OH)D serum concentration up around 200 nmol/L (80 ng/mL)... and in the process, prevent your CH.
If you have any questions, you know were to find me. I'm here to help.
Take care and please keep us posted.
V/R, Batch