I think if your new glasses cause headaches your optometrist might have fucked up something, either your prescription/diagnosis or the tech who installed the lenses in the frame didn't center them to your IPD/distortion angle correctly.
The biggest thing is that your eyes will naturally "strengthen" to make up for loss of acuity with an old prescription and a new prescription will correct that immediately and thus you end up with a mismatch that takes awhile to settle.