Does she randomly scratch/nip throughout the day or do you notice she does it more after a walk or have been outside? You can try wiping her down after every outing with puppy wipes or baby wipes (for sensitive skin only) see if that helps.
Do you use something like Fabreeze or some other odor eliminating product?
I'm assuming you're feeding her whatever the previous owner was feeding. But you could also try giving her blend meals for a while to see if makes any difference as well.
This is more like a guessing game and process of elimination. It'll take some time but I'm sure you'll be able to find a solution one way or another.
Btw, congrats on your new furbaby!!!!!