Thank you for the additional information.
One of the first things I would suggest is switching flea preventions. One of the most common reasons for itching in these areas is an allergy to fleas. In all honesty Hartz products do not work and they have a very high rate of adverse reactions. Dog that have flea allergies will react not only to the bite of the flea but also to the saliva left behind.It only takes the bite of one flea to set off a reaction. I would suggest Advantage which is now available over the counter at most pet stores.
Here is additional information on flea allergies LINK
I have also reviewed the ingredients in the allergy tabs and not sure how they would even work on itching so I would not waste any more money on those. What you can use instead is human Benadryl at a dose of 1-2 mgs per pound of body weight every 8-10 hours. Using generic is fine.
I doubt this is do to the food as with food allergies we also see in most cases itching in the ears and paws as well. If this was due to food then it can take as long as 12 weeks to see a difference.
I would also suggest not bathing as often as this strips the natural oils from the skin and can make itching worse.
I would switch flea preventions and try the Benadryl and hopefully this will help.
One other thing that may be helpful is to add Omega fatty acids to the diet daily.
I hope this helps and she feels better soon. Please reply back if you have additional questions or concerns and I will be happy to continue.