There are a number of things that can cause scratching in dogs. In young dogs, my first concern is Sarcoptic mange. This is REALLY itchy and will cause hairloss and a secondary skin infection. Where on Foxy's body is she scratching the most?
Are you using a flea preventative on her right now?
Sarcoptic mange is caused by a very small mite that burrows into the skin. It is quite contagious between dogs and puppies. It can also cause a localized, VERY ITCHY rash on people. It can be diagnosed sometimes with a skin scrape by your regular vet, although the mites can be very hard to find. Usually, if we suspect the dog has this type of mange, we just treat with ivermectin. It is usually given by mouth every 2 weeks for 3 treatments.
If you aren't using a flea preventative currently, I would make sure to apply one, even if you aren't seeing any fleas. In some sensitive dogs, just a single flea bite is enough to cause excessive scratching and hair loss. A preventative is unlikely to harm Foxy and it will completely eliminate the possibility of fleas.