Yes, please, please Vet her before trying remedies yourself. You say she is a stray so can you be absolutely, positively certain there is NO collie type of breed in her background? No, you can't because even if she was an F1 cross she could look completely like one breed and not the other. It's important because collie types and mixes may be sensitive to invermectin. Plus in the meantime she could be spreading whatever she has to you and your other dog.
Great you took her in, thank you, poor little thing. Photos?