Primary<unk> Migraine
Tension
Cluster
Secondary<unk> Viral illness and fever
Post-traumatic
VP shunt malfunction
CO poisoning
Epidural hematoma
Subdural hematoma
Brain abscess
Pseudotumor cerebri
Meningitis
Space-occupying lesion
AVM
Sinusitis
Dental abscess
Otitis media
CNS tumor
Migraine
Tension
Cluster
Viral illness and fever
Post-traumatic
VP shunt malfunction
CO poisoning
Epidural hematoma
Subdural hematoma
Brain abscess
Pseudotumor cerebri
Meningitis
Space-occupying lesion
AVM
Sinusitis
Dental abscess
Otitis media
CNS tumor
Headache 
Primary headache
Tinnitus
Migraine
Dizziness
Tension
Sore throat
Cluster