Flashes could be a "symptom" of ON, but can also occur for other reasons. The key ones that jump to my mind are retinal detachment (easy to see with an ophthalmoscope) and damage to the visual cortex. Since Leslie didn't say if this is in one eye or both, that complicates things. I have damage to my right optic nerve and right optic tract with a positive VEP and never had a single flash. All I had was a sore eye and then someone pulled a brown shade over my right eye.
The best bet would be a referral to a neuro-ophthalmologist to figure things out. All the stated symptoms don't really support any clinical diagnosis. You need some clinical signs (VEP, OCT, MRI) to complete a diagnostic picture.
Bob
Flashes are signs that the optic nerve's been damaged. I've had this flash of what looks like static in my right eye, and I've had the black/white blip in the right eye since my first flare.
Flashes are not typical in Optic Neuritis. Also symmetric symptoms (both arms or both legs) are not typical of MS. Constipation is more typical than diarrhea. I would side with Jen and suggest that you just list the symptoms and timeline for your doctor and let them diagnose. If your doctor feels that you might have a neurologic condition, they will refer you to a neurologist. The Neurologist will typically order an MRI if there is any indication of neurologic disease.
Bob
The best thing to do is not tell your doctor that you've been looking up symptoms. They'll stick you in the conversion disorder hole and assume that you've got psychiatric issues.
This doesn't mean, however, that you have MS. There are several other issues that can cause the same symptoms. The best way to get treatment is not to self diagnose - let the doctor figure out what's wrong, and treat you for your symptoms.
It would be in your best interests to create a timeline of your symptoms - when they first appeared, how long they lasted, and when/if they went away.