Upper respiratory infection, influenza<unk> 
Juvenile nasopharyngeal angiofibroma
Nasal polyp
Nasal mass
Nasal foreign body
CSF leak (e.g. basilar skull fracture)
Toxic inhalation (e.g. selenium toxicity, neurotoxic shellfish poisoning)
Migraine headache
Tension headache
Cluster headache
Meningitis/encephalitis
Neoplastic meningitis
Myocardial ischemia
Retropharyngeal abscess
Intracranial Hemorrhage (ICH)
SAH / sentinel bleed
Acute obstructive hydrocephalus
Space occupying lesions
CVA
Carbon monoxide poisoning
Basilar artery dissection
Preeclampsia
Cerebral venous thrombosis
Hypertensive emergency
Depression
Neoplastic meningitis
SAH / sentinel bleed
Giant cell arteritis of temporal artery (temporal arteritis)
Idiopathic intracranial hypertension (Pseudotumor Cerebri)
Acute Glaucoma
Acute<unk> 
Cavernous sinus thrombosis or cerebral sinus thrombosis
Carotid artery dissection
Trigeminal neuralgia
TMJ pain
Post-lumbar puncture headache
Dehydration
Analgesia abuse
Various ocular and dental problems
Herpes zoster ophthalmicus
Herpes zoster oticus
Cryptococcosis
Febrile headache (e.g. pyelonephritis, nonspecific viral infection)
Ophthalmoplegic migraine
Superior Vena Cava Syndrome
Viral
Varicella
Herpes
Enterovirus
West Nile
Tuberculosis
Lyme disease
Syphilis
Leptospirosis
Fungal (AIDS, transplant, chemotherapy, chronic steroid use)
Noninfectious
Sarcoidosis
Vasculitis
Connective tissue disease
Drug induced aseptic meningitis
Varicella
Herpes
Enterovirus
West Nile
Sarcoidosis
Vasculitis
Connective tissue disease
Drug induced aseptic meningitis
Sinusitis
Upper respiratory infection, influenza
Laryngitis
Mastoiditis
Juvenile nasopharyngeal angiofibroma
Croup
Nasal polyp
Pharyngitis