Folks with MS are going to sympathize with me on this one, while folks who don't have it won't really understand.
Yesterday, I woke up with a nasty headache, centered behind my right eye.
Folks without MS: Sounds like a sinus headache.
Folks with MS: Oh, no! Was it optic neuritis?
Since my major attack was a bout of optic neuritis, that came to mind first for me. Time to panic. So I take some Tylenol (the only thing we pregnant women are allowed to take for pain), and check to see if my vision is blurry. No. Not yet, at least. A few hours later, when the headache is still nasty, I take more Tylenol and check my vision out of that eye again. Still OK. Finally, I just can't take it anymore, and I leave work, head home, and take a nap. Ah, headache better. Time to stop being scared.