Did you fill out a found report with Upper Credit? I would also have her scanned for a chip. She also might have a tattoo in her ear? She sounds like a calico.
Since she is so skinny, I would take her to a vet..see if they can take her in? If she is skinny, she is mostly likely dehyrated and may need to be on fluids? I know that some vets will take in strays and find them homes.