Sorry to hear of Dandee's skin problem.
Unfortunately the route of her problem could be:
Mange - caused by skin mites.
Bacterial skin infection.
Fungal skin infection.
Or a combination of the above.
This is why your vet wanted to take a skin scraping, that way the lab will analyse the sample and probably grow it up in the lab, then they will test to see what medication will kill the culprit. This way you find out precisely what is causing the problem and the best way to treat it. Although it may seem expensive, it is often cheaper in the long run, than trying many different medications, with non of them working.
The topical spray you had was an antibiotic, with a steroid component to try and reduce the itch, the powder could have been an antibiotic, or an anti fungal.
I'm going to link you to a couple of web sites:
I have copied you the following sections from goatworld.com. There is information on different skin conditions and how to treat them.
DermatitisIt could be many types, severity and symptoms depends on the cause and sites affected like:
Mange (Sarcoptes, Demodatic and Psoroptes)Clinical symptoms: Flakey scruffy dandruff on the skin, severe itching, hairlessness develops and the skin becomes thick, hard and corrugated.
Preventive care: Skin scraping examination is essential. Clip hair and wash with warm water and soap. Apply 0.5% malathion or 0.5% Seven or 0.06% Lindane as spray, Swab or dip thrice at the interval of 7 days. Diptrex ointment 1% is effective.
Ring worm (Fungus)Clinical symptoms: Inflammation of hair follicles, falling of hairs, lesions are circular on the face, shoulder, neck, eyes, irritation and rubbing, thick crusts or scales may appear.
Preventive care: After clipping hair and scrubbing with water and soap, apply acid salicylic or benzoic acid ointment 2.5% or tincture of iodine once daily till lesions heal or zephirin.
I hope this information is helpful. Kind regards XXXXX XXXXX