Welcome Ry! From my own experience, it can take months for symptoms to resolve. When I was "officially" diagnosed three years ago, I had severe double vision which took about three months to get better. Unfortunately, my depth-perception is toast and I have some color blindness. I get constipation too, which is no fun. Mine mostly occurs about a week before my period. What I hate is that it's much more common now. If anyone has any brilliant ideas on ways to prevent it, I'm all ears!
As far as the blood tests go, I had a similar experience. I had optic neuritis about ten years ago and everything came back negative. I had an MRI, lumbar puncture, and a bunch of blood draws all for the doctors to say, "we don't know what's wrong with you!". They put me on Solu-Medrol for three days and then prednisone. Since then, I know I had symptoms that no one picked up on. I hope this helps!