Suggest you make contact with you excellent support group: Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

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I have never seen any reports associated autoimmune disorders with Cluster. And, yes, you can have other types of headache as well as Cluster.
I understand that you have the right to ask for referral to a headache clinic of your choice, by-passing the usual referral procedures. (Might confirm with the OUCH group, the original source of this information.)
That you have a neurologist in your camp is important. Hope he has experience with headache disorders for many of them have no skill working with Cluster.
See the PDF file, below. These are the kinds of meds which are commonly used for Cluster. If you are not being given meds from this list, it's time to discuss the doc's experience with him.
Educating yourself about Cluster is essential for knowledge gives you skill and reduces anxiety. Explore your OUCH site; the buttons to the left, here, starting with the OUCH site. Also,
Cluster headache.
From: Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

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(Orphanet Journal of Rare Diseases)
[Easy to read; one of the better overview articles I've seen. Suggest printing the full length article--link, line above--if you are serious about keeping a good medical library on the subject.]
Leroux E, Ducros A.
ABSTRACT: Cluster headache (CH) is a primary headache disease characterized by recurrent short-lasting attacks (15 to 180 minutes) of excruciating unilateral periorbital pain accompanied by ipsilateral autonomic signs (lacrimation, nasal congestion, ptosis, miosis, lid edema, redness of the eye). It affects young adults, predominantly males. Prevalence is estimated at 0.5-1.0/1,000. CH has a circannual and circadian periodicity, attacks being clustered (hence the name) in bouts that can occur during specific months of the year. ALCOHOL IS THE ONLY DIETARY TRIGGER OF CH, STRONG ODORS (MAINLY SOLVENTS AND CIGARETTE SMOKE) AND NAPPING MAY ALSO TRIGGER CH ATTACKS. During bouts, attacks may happen at precise hours, especially during the night. During the attacks, patients tend to be restless. CH may be episodic or chronic, depending on the presence of remission periods. CH IS ASSOCIATED WITH TRIGEMINOVASCULAR ACTIVATION AND NEUROENDOCRINE AND VEGETATIVE DISTURBANCES, HOWEVER, THE PRECISE CAUSATIVE MECHANISMS REMAIN UNKNOWN. Involvement of the hypothalamus (a structure regulating endocrine function and sleep-wake rhythms) has been confirmed, explaining, at least in part, the cyclic aspects of CH. The disease is familial in about 10% of cases. Genetic factors play a role in CH susceptibility, and a causative role has been suggested for the hypocretin receptor gene. Diagnosis is clinical. Differential diagnoses include other primary headache diseases such as migraine, paroxysmal hemicrania and SUNCT syndrome. At present, there is no curative treatment. There are efficient treatments to shorten the painful attacks (acute treatments) and to reduce the number of daily attacks (prophylactic treatments). Acute treatment is based on subcutaneous administration of sumatriptan and high-flow oxygen. Verapamil, lithium, methysergide, prednisone, greater occipital nerve blocks and topiramate may be used for prophylaxis. In refractory cases, deep-brain stimulation of the hypothalamus and greater occipital nerve stimulators have been tried in experimental settings.THE DISEASE COURSE OVER A LIFETIME IS UNPREDICTABLE. Some patients have only one period of attacks, while in others the disease evolves from episodic to chronic form.
PMID: 18651939 [PubMed]
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Follow your doc's guidance for some months before being tempted to try other treatments. It takes some time to adjust dosing on meds and to give them time to become effective before making any judgments about how effective the treatment plan is.
If you have a good paper supply, print out this free manual for a general overview. Written by one of the better headache docs in the U.S.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

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ALL NEW!! HEADACHE 2010-2011
Robbins Headache Clinic
Free, 50-page. Covers all major headache Dx and
related issues.
In a PDF file.
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Finally, read the messages here; ask specific questions.