A one-sided throbbing headache behind the eye, with no vision change and a partial response to medicine, often points to a first episode of migraine, though sinus-related pain can look similar early on. Pain shifting from behind the eye to the back of the head over two days still fits that pattern.
Next Steps
Resting in a dark, quiet room, staying hydrated and not skipping meals often helps during an attack. If the pain keeps returning or changes pattern, please see a general physician or neurologist for a proper diagnosis and a suitable plan.
Health Tips
Seek urgent care if this becomes the worst headache ever, comes with fever or neck stiffness, or any new vision or limb weakness appears.