There must be something wrong with her diet or water she drinks or takes bathes. Consult a vet and describe all these issues.

Does she scratch all time?

Indeed

Please share a picture for reference

Do not consider my comment as medical advice, it's only my opinion. Sometimes too much medication and creams etc can also irritate the skin. If those medicines haven't been working you can do things. First get her blood tests done for infections or any other serious disease. If she is healthy inside then maybe she has sensitive skin. Second you can try home remedies. Some examples- 1. Adding a teaspoon of Pure cold pressed coconut oil in her meal every day 2. Adding a pinch of turmeric in her meals 3. Applying turmeric paste on her body mixed with milk before giving her a bath. 4. Give her a spoon of Salmon lol daily. 5. Give her supplements for necessary vitamins. 6. Add neem leaves to her bath water. All these might help alleviate her situation.