Here's an interesting article:www.webmd.com/eye-health/double-vision-diplopia-causes-symptoms-diagnosis-treatment?page=3
From Page 2 that hopefully you've already been asked:
Focus on something unmoving in your field of vision -- a window or a tree.
Are the two objects side by side, or is one on top of the other? Or are they slightly diagonal? Which one is higher or lower?
Are both images clear but simply unaligned with each other? Or is one image blurry and the other clear?
Cover one eye, then uncover it and cover the other. Does covering either eye make the double vision go away?
Pretend your field of vision is a clock face. Move your eyes around the clock, from noon to six and up to 12 again. Is your double vision worse at any clock position? Does any position make your double vision improve?
Tilt your head to the right, then to the left. Do any of these positions improve the double vision, or make it worse?