I've heard O.N. is painful - is this always the case?

I got curious about O.N. because the last 2 days, I've had a spot in my left field of vision that's 'gray' or blurry. When I try to look with that left eye only, I see things very dulled/gray (like black text on white looks gray and almost like pencil that someone's erased parts of).

I was told my optic nerves looked to be in great shape, so now I'm concerned that perhaps I've since developed (or started to develop) O.N. This isn't painful, and not completely encompassing the entire eye.

(just noted - when I look at a white wall, the spot looks more like what you'd see if you were to stare at a bright light too long.. only it doesn't disappear).

Luckily I'm already lined up this month to see my GP... and review my last MRI scans, or discuss my next neuro appointment to do so. I'll have to bring this to her attention if it doesn't subside. I guess it's off to the ER if it doesn't improve. Sigh....

Stinking MS!

.... granted this may not be MS alone. I had a wicked vicious headache yesterday (probably more in line with migraine) so I'm wondering if the eye issue may be more migraine related. The headache was across the forehead, but more pronounced on the left (as is my neuralgia in general).