Flare-up

I was diagnosed with NMO 3 months ago. My symptoms are numbness from waist down to toes. Physical Therapy was working wonders, I was walking most of the time withouty cane. I got a cold and flu about a week ago, and now most of the numbness is back and Im back to a walker. My neougolist said its a flare-up not a relapse because of no.new symptoms. Has anyone else experienced a flare-up during a cold?
Mike