I would agree with the others. If a cat stops using the litter box they are trying to tell you something. Need to see a vet ASAP.
If the vet doesn't find a problem right now - one of mine had cancer and they couldn't find it for a long time. Anyway - one of mine now has a behavior issue and Prozac a $4 script from Wal-Mart works wonders. One 1/4 to 1/2 pill a day keeps him right.
Also does the quilt have wool? I had a feather duvet once. It went to the dumpster. Strange smells will set them off as well.
I had a vet tell me once that no self respecting cat can walk past a basket of laundry. Well, we just learned to adjust to things so it wouldn't set them off.
I do find that a Feliway plug in also helps - Amazon.com has the best price on those.