It's possible that the brief headache is due to confusion between vergence and focus. I.e., your brain is going "my eyes are converging a point 30cm away, so why am I focusing as though it's infinitely far off?!"

If this is the case, adding base-out prism to the lenses could (in theory) solve problem.

https://www.eophtha.com/posts/fun-with-prisms-in-ophthalmolo...