Hi there and good morning....sounds like u are managing your MS very well, with the help of Rebif, and of course some things which I am sure that u do to minimize fatigue, etc.....
Then all of a sudden things go into the toilet abit - my guess is that you are going thru a relapse. I am very much like your self, as I do pretty darn good almost everyday - if I rest when I get tired, and stay out of the heat, I can have symptom free days.
However about a month ago, I started to have vision problems, some dizziness came back, really tired, etc - and as it turned out, I had a scheduled neuro appointment during this time - perfect timing I must say.
He advised me that I was having a flare up, and buried or old symptoms and even new ones will surface.
But that all past in a short period of time, and back to where it was before - hurray!
So my guess is that you are having a flare up...