Over the past few weeks I’ve been dealing with godawful toothaches/headaches, and a few times I glimpsed the ur-headache from which all others descend. For your enjoyment, here are some lesser-known varieties of the species:
Transtherial neuralgia: The etheric twin to a nerve cluster one one side of your head has become irritated and inflamed, causing debilitating pain through the eye, sinus, and jaw on that side. If left untreated, the psychic impaction will fissure open, splitting your mandible on one side as spined, curving growths of tangible astral pain erupt from your flesh.
Lithophthalmic: Your eye or eyes begin turning to stone (not to be confused with ossuophthalmic, when the eyes ossify into bone). The first symptom here is a painful heaviness in the eye as the humours begin solidifying. After several days this will proceed to blindness as the rest of the eye follows suit. Finally, the rods and cones change into new arrangements of stony cells, strange striations that allow sight only through solid stone. Of potential use, if the pain is worth dealing with.
Superspectral: Due to encounters with extradimensional forces, the topology of your soul has been changed. As your consciousness is being rearranged, parts of your mind begin shifting, sliding, and skipping across the occult superspectrum. At times your skull might be visibly illuminated from within by previously-unseen and -unseeable colors. At other times your eyes, nose, mouth, and ears may drip and leak otherworldly music that cuts like barbed hooks. None of this feels good.
Greater scintillating scotoma: Imagine the aura that accompanies visual migraines, only the aura starts puckering and ripping open and things start coming out and only you can see them, but also you have a debilitating migraine.
Buscard's pleromalphasia: Parasitological linguistic infection causes the language centers of your brain to become increasingly efficient. At first this can be helpful, as you pick up new languages remarkably quickly and can follow deductive leaps from the barest of philological information. Unfortunately, the condition doesn't stop at being helpful, and soon your mind is crowded with words, too many words, sentence structures of impossible languages, new declensions that contort your ability to reason or function beyond the point of failure.