Figuring out what to wear during a flare (a period of increased disease activity) is a challenge. You feel your absolute worst when flaring. Instead of pulling on sweats, I try to select comfy lounge pants with a coordinated top (I say "try," because I'll admit that I don't always succeed). A scarf and cardigan add warmth and style. Loafers are like socially acceptable slippers.
While you might not want to wear this outfit to work unless your office is very casual, it would be perfectly appropriate for your errands or doctors' appointments.