I agree the losing 2 lbs in two days needs a call to the vet just to make sure everything is ok.

I know our furry kids get upset and wont' eat or if they do they barf it back up. I cat sat for several years a gang of 3 (outdoors/indoors) and whenever mom/dad went out of town for couple days to week esp near holidays, I would find food barf down sidewalk of the apartment complex for first couple days they were gone then they were ok when they saw me come on regular basis (2 x a day).