Brain tumor? i notice one pupil is just slightly larger than the other pupil. this happens to be the eye i get migraines in.

Probably normal: Some people naturally have one pupil larger than the other. If you haven't talked with a doctor about your migraines, you should, just to be sure there is nothing unusual about them.

Unlikely: Brain tumors are rare.If that is the i you get your migraines in most likely why the highest dilated.Check your eyes when you do not have a headache 10% of the population as a dilated pupili do not know how long you've had your headaches but optic neuritis would also need to be considered.If you not not had your headaches evaluated i recommend that you get your headaches evaluated.