I am sorry to hear you are worried about Little Bit and that she has valley fever. My name is Rebecca. I am a veterinarian and will do my best to help.
Is she getting any medication for vomiting? Have any Xrays been taken?
Have any blood tests been done to check for things like pancreatitis or liver disease that might be causing the vomiting?
If she were mine, I would be doing blood tests to check liver, kidney, and pancreas values. I would be giving injections of Cerenia for the vomiting. If she can't keep anything down, I would be giving her fluids by IV or under her skin to keep her hydrated.
Valley fever is bad news, as you know, and once infected she may be infected for life. The poor little dog probably got it when she was abandoned in the desert. You might consider seeing a specialist, like a board certified veterinary internist, if you or your veterinarians have not been consulting with one till now.
I am sorry you did not get help from an expert sooner. I just came online and took your question as soon as I saw it. Let me know what else I can help with. Rebecca