Skin problem with my little dog? 10 points!?

My Cavalier king charles has a severe skin problem. She has been to the vets who thinks its fleas. So i went home with anti-inflamatories and medicated shampoo. She was treated fully but has gotten worse. She is in terrible discomfort so i talked to the vet who says its hard to tell with skin what it could be. I think it could be sarcoptic or demodeptic mange- but deffinately not fleas. Anyway the vet gave us plenty of antibiotics and told me to keep using the medicated shampoo. So far, no improvement. I have other dogs and all of them are perfectly fine!! Even the cat shares the bed with her and he’s ok too. Any advise, tips or help guys? I cant stand to see her like this, it came on so suddenly too. Her skin is all scabby and crusty and she has a bit of hair loss.
The vet gave us an appointment again for next week, should i ask for a skin scraping?
Thanks

Allergies or mange. Get a skin scraping to rule out mange, but also test for food allergies. What are you feeding her? Many dogs are allergic to grains in dog food, or even some of the proteins, and it manifests as skin problems. I had a similar problem with my dog and tried everything for dry skin- supplements, oatmeal baths, flea tests and treatments, etc. Some of these helped, but it didn’t go away until i switched him to a higher quality food with no corn.

Good luck!