When I have brought new cats home - two rescues, one from the Humane Society - I do keep them in one room to begin with, for at least a week.

While she is in there, get some Cat Attract litter to encourage her to use the box. She may still have some feral habits.

The first thing I think of when this happens is a urinary infection. If you can't get a urine sample, take her to a vet. Hopefully the shelter has a vet that is low or not cost.

Please keep us updated on sweet Lola. Bless you for adopting her!