I have had lots of training in Dermatology but I am not board certified and you may eventually want to seek out a specialist in that area. SO ...what you are getting is my opinion only.
Skin disease is the hardeset to manage. It is the body's largest organ and it takes more medication and longer time lines to treat...and many times there is no cure with skin disease just management.
Primor is a good antibiotic but the best skin antibiotic for long term use and efficacy is Cephalexin. Benadryl is a good antihistamine for allergic reactions to bug bites and so forth but a very weak antihistamine for long term underlying allergies in dogs...Use of hydroxyzine (atarax in humans) and some of the stronger ones have better results.
Vitamins are great...DermCaps with the OMEGA FATTY ACIDS and FISH OILs are the best...they are balanced with the Vitamin E and make sure you have Vitamin C somewhere in the mix.
Topical shampoos should contain no soap and be microencapuslated components of antihistamine or topical antipruitic mixes. There are also good stay on creme rinses.
Try to stay clear of the Kenalog, instead request small quantities or oral steroids...Because once the steroid is in the body...you can't get it out and if she develops an infection there can be problems. (I use injectable, but not for longterm allergy dogs). There is a pill called Termaril-P which has a low grade steroid and antihistamine...I would use this for a week or so while you try to get things under control...and use as needed on bad weeks...but understand that steroids need to be started and weaned off.
When I start people on this "we are getting serious" approach to the skin, the food I select is usually Science Diet Z/D because it is all synthetic proteins and meant to eliminate everything that could possible be an allergy and starts the dog "fresh". It is my choice...and then from there we find a diet to manage them on after we have "cleared" them up.
Lastly, somewhat new on the market for Atopic dogs, those we believe to have significant allergy issues, is Atopica which is a medication to help longterm dog allergies...you can ask your vet if this would help your dog.
I know you will have more questions...please let me know.