Becky/Anissa:
I'm certainly not a doctor but to the best of my (admittedly limited) knowledge the radio waves and magnetic field employed by the MRI scanner shouldn't cause headaches. For what it's worth, I've undergone 7 or 8 MRI scans in the past 3 years, all of them using the contrast agent (gadolinium), and never experienced a headache, later. The gadolinium might generate an allergic reaction but I believe this is quite rare and I don't think the reaction would be a headache or dizziness, although, again, I'm not an expert on this subject, just speculating. I would have to consider the stress involved both before and after the MRI as a possible contributing factor to a headache, although I'm not sure how stress would generate dizziness, although, immediately after the MRI scan is completed, I usually need a few moments to regain my sense of balance after lying flat and perfectly still for over 40 minutes. Unless the dizziness and headaches increase in intensity or do not resolve within 24 hours, which would prompt a call to my doctor, I would have to view them as an unpleasant after-effect of a very necessary test.
Jim