I recently discussed headaches and the various mechanisms that can cause them.

Firstly, no pain without ((Nervous - Sensory Innervation|sensory nerves)). As we know, the brain itself has no sensory innervation, simply an impact point or regeneration phase in the brain relays don't cause pain. Sensory innervated structures in the area are ((Circulatory - System Overview|blood and lymph vessels)), ((Nervous - Brain - Meninges|meninges)), and the pericranium (((Musculoskeletal - Periosteum (Visceral Fascia)|periosteum)) of the skull). Pressure on these structures, like local tumors or edema, can cause pain, as does inflammation. Thereby, deep regeneration phases accompanied by ((Urinary - Kidneys - Collecting Tubules|water retention)) in the affected relays can cause headache.
Inflammation in the ((Sensory - Ears - Eustachian Tube|middle ear)) and ((Respiratory - Nasopharyngeal Mucosa |nasopharynx)) as well as in the sinuses also causes pressure.

Histamin like in certain foods & drinks can also trigger headache: this is a "chemical warning trigger" hinting at the circumstances of the UDIN.

Headaches can be due to increased blood flow and -pressure to the brain like in overthinking, or to spasms in the vessels like in a healing peak. Migraines can be connected to hormone levels, or hormonal triggers.
Hypertension in ((Musculoskeletal - Skeletal Muscles|muscles))/((Musculoskeletal - Muscle Fascia|fascia)) can lead to headache: typical are tight neck muscles, ((Nervous - Facial Nerve|facial)) muscles or strained ((Sensory - Eye Muscles|eye muscles)).

The dramatic, short cluster headache in the forehead seems to appear in the healing peak of the frontal (fear) relays.

Interestingly, meningeal and periosteum sensitivity seems to follow the Inner Skin pattern with hyperesthesia in stress phase, therefore a cold, helmet-like headache or migraine accompanied by low blood flow in the area can appear in the respective stress phase.

So, a specific description is needed to precisely identify what tissues are affected: warm or cold feeling? Time or rhythm of appearance? Quality of the pain? Certain triggers?
Having that said, it's always the stressors that are the problem, even in regeneration phases, like the expectation of pain...

Please add your experiences and insights!