Great Pyreneese with Lupus

[Grandma C]

My great pyreneese is about 9 mo old and 2 !/2 mo ago she became ill with hair falling out severe itching sores and scabs everywhere even in her ears. She quit eating and became lethargic and just generaly pitifull. The Veterinarian thinks it might be lupus because she tested negative for mange and everything else. We did not have her checked for lupus because of an astronomical Veterinarian bill. She is on prednisone, Prilosec and benedryl. and perks up pretty well with hair growing back in but a few days after we back down on the dosage of prednisone she gets sick again. Has anyone got any suggestions where to go to maybe get more information. Maybe someone very familiar with the breed and breed specific problems or needs nutritionaly.
If this continues we will have to euthanize her because of the expense. I have 4 other dogs that are rescued dogs and just can't afford to take care of a high maintanance pet. She is such a sweet pet and guards our 4 goats.
Grandma C