yes the reply below has a good point, has she a yeast infection on moist areas, paws, wrinkles, private areas, try for at least a couple weeks , mix 50/50 vinegar water, and wash these areas daily, it raises the acid content and will not grow yeast,(but if the vet says she has no yeast,-it will keep it form occurring ever again) but she will need antibiotics if she has one now. this is similar to a douche for women or athletes feet on men. same deal, but vinegar is natural.
these are the most common reasons to lick or chew,
the wrong food
soaps that are perfumed,
rugs that are not rinsed enough with clear water
growing things,( it helps a lot to dip the dogs feet into a bucket of warm soapy water on coming inside.)
these are just the normal things. it can also but rarely be fleas, usually that is a but itching,
go through the above items, and keep trying things. I am sure one of us will come up with an idea that will work. good luck.