Hello. I am sorry to hear that Topaz is having some trouble. My name is ***** ***** I would be happy to help.
One problem we have here with trying to treat this at home is that we do not know what this is we are trying to treat. It could be a bacterial infection, fungal infection or even mites.The area that this is located in can also be due to fleas even if you are not seeing them. This is a pretty typical area for a dog to bite when there is a flea allergy. If she has an allergy it only take the bite of one flea to cause a reaction because they react not only to the bite of the flea but also to the saliva and flea dirt left behind.
The other thing we have to consider is that she could be painful in that area and that is what is causing the biting.
The one sure things is that we need to keep her from chewing the area even if this means you have to use an e collar for a few days. If she continues to bite/chew/lick etc at the area then it will not heal.
It would be best to have her seen by a vet and have a quick inexpensive skin scraping done to see if this is fungal or bacterial in nature and to make sure that oral meds are not needed.
Until you can get her seen I would suggest the following.
1. Make sure you are using a high quality flea prevention, nothing by Hartz, Sergents, Zodiac or Frontline
2. Get an e collar at the pet store or a vet close to you
3. Clean the area twice daily with a wound cleanser such as Hibiclens or Betadine diluted with water to the color of tea. Alternate hydrocortison cream and antibiotic cream using each twice daily.
4. Oral Benadryl can help reduce the itching. This is dosed at 1-2mgs per pound of body weight 2-3 times per day.
I hope this helps and she feels better soon. Please reply back if you have additional questions and I will be more then happy to continue. If you have no additional questions please take a few moments to provide a rating so that I am compensated by justanswer for assisting you.