Translation:My head hurts.
I think translating this as headache should be acceptes as a natural translation.
I did as well! I think I commented to see if people thought that was unreasonable.
Though later I noticed duolingo translations using headache in longer sentences so it probably should be changed.
It's simpler than that: there are usually many ways to phrase a translation, and not all the common ones will be added at the time of v1.0.
It's painfully noticeable when you're trying to test out of a course <.<